/ I DEPARTMENT OF THE INTERIOR 

q q UNITED STATES GEOLOGICAL SURVEY 

\ r\<~\ (- GEORGE OTIS SMITH, Director 

t? SG& I Water " Sijpp]ly Papeh 232 

UNDERGROUND WATER RESOURCES 
OF CONNECTICUT 

BY 

HERBERT E. GREGORY 

WITH 

A STUDY OF THE OCCURRENCE OF WATER 
IN CRYSTALLINE ROCKS 

BY 

E. E. ELLIS 




WASHINGTON 

GOVERNMENT PRINTING OFFICE 
1909 




aass QtS)0\ £ 

Book i 



DEPARTMENT OF THE INTERIOR 

UNITED STATES GEOLOGICAL SURVEY 

GEORGE OTIS SMITH, Director 



Water-Supply Paper 232 



UNDERGROUND WATER RESOURCES 
OF CONNECTICUT 

BY 

HERBERT E. GREGORY 

WITH 

A STUDY OF THE OCCURRENCE OF WATER 
IN CRYSTALLINE ROCKS 

BY 

E. E. ELLIS 




WASHINGTON 

GOVERNMENT PRINTING OFFICE 

1909 






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t 



OCi 23 

». of a 



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CONTENTS. 



Page. 

Introduction 9 

Chapter I. Geography 11 

Topography 11 

General relations 11 

Physiographic features 12 

The highlands 12 

The western highland. 12 

The eastern highland 14 

Valleys in the highlands 14 

Central lowland 16 

Extent and character 16 

Lava ridges 16 

Farmington and Connecticut valley lowlands 17 

Coast line 17 

Drainage 17 

Forests 20 

Climate 20 

Meteorological data 20 

Summary 26 

Surface-water supply 27 

Source and character 27 

Quantity available 28 

Population and industries 30 

Chapter II. Geology 31 

Outline of geologic history 31 

Descriptive geology 34 

Introduction 34 

Crystalline rocks 35 

Distribution and character 35 

Joints 37 

Faults 38 

Triassic sandstone and trap 38 

Distribution 38 

Stratigraphy 38 

Joints 40 

Faults 41 

Pleistocene drift 42 

Distribution and general relations 42 

Character cf material 42 

3 



4 CONTENTS. 

Page. 

Chapter III. Occurrence and recovery op ground water 44 

Circulation of ground water * 44 

The water table 44 

Movement of ground water 45 

Porosity 45 

Permeability 46 

Artesian conditions 48 

Springs 50 

Amount of ground water 51 

Temperature of ground water 52 

Contamination 53 

Chapter IV. Ground water in the crystalline rocks op Connecticut, 

by E. E. Ellis 54 

Introduction 54 

Literature 54 

Distribution and character of crystalline rocks in Connecticut 56 

Rock types 56 

Granite 58 

Gneiss 58 

Schist 58 

Quartzite schist 58 

Pegmatite 59 

Trap rock 59 

Limestone ■. 59 

Drilling products 59 

Drift 60 

Conditions affecting occurrence of water in crystalline rocks 60 

Introduction 60 

Joints 61 

Vertical joints 61 

Horizontal joints 62 

Relations of rock type to jointing 62 

Joint direction 63 

Structure planes 63 

Variation in jointing 63 

Faults 65 

Circulation and storage of water 65 

Influence of joints and other openings 65 

Spacing of vertical joints 65 

Spacing of horizontal joints 66 

Continuity of horizontal joints 66 

Continuity of vertical joints 67 

Fissility and schistosity openings 67 

Intersection of fractures 67 

Opening of joints 68 

Number of contributory joints 70 

Water level 70 

Direction of circulation 72 

Decomposition as a measure of circulation 73 

Storage of water 74 



CONTENTS. 5 

Page. 
Chapter IV. Ground water in the crystalline rocks op Connecticut, 

by E. E. Ellis— Continued. 

Tabulated well records 77 

Practical applications 91 

Percentage of failure of wells 91 

Variations in yield and depth 92 

Limit of depth for wells in crystalline rocks 93 

Quality of water 94 

Temperature of water 94 

Location of wells 94 

Constancy of yield 95 

Flowing wells 9(5 

Wells in varying rock types 97 

Wells in granite 97 

Wells in schist and gneiss 98 

Wells in quartzite schist 99 

Wells in phyllite 99 

Wells in limestone 99 

Wells in granodiorite 100 

Statistical tables 101 

Chapter V. Ground water in Triassic sandstones and traps 104 

Introduction 104 

Water within the rocks 104 

Conditions of occurrence 104 

In sandstone 104 

In conglomerate '. 106 

In shales 106 

In trap 107 

Water in bedding planes 107 

Conditions of occurrence 1 107 

Black shale 109 

Water in joints 109 

Vertical and horizontal joints 109 

Direction and continuity of jointing 112 

Spacing of joints 112 

Opening of joints 113 

Joints in trap 113 

Water along fault lines 114 

Records of wells in Triassic sandstones, conglomerates, and shales 115 

Wells in trap 128 

Practical applications 130 

Yield of wells 130 

Depth of wells 131 

Quality of water 132 

Temperature 132 

Height of water in wells 133 

Flowing wells 133 

Location of wells 135 

Statistical tables 136 

Chapter VI. Water in the glacial drift 138 

Introduction 138 



6 CONTENTS. 

Chapter VI. Water in the glacial drift — Continued. Page. 

Character and water capacity of drift 138 

Till 138 

Stratified drift 139 

Clay 140 

The drift as a water reservoir 140 

Water bed at contact of rock and drift 142 

Wells in till and stratified drift 142 

Water horizon 143 

Depth and yield 144 

Quality of water 145 

Water level 146 

Cost of wells -. 147 

Records of wells in till. 147 

Records of wells in stratified drift 151 

Chapter VII. Water supply op typical areas 157 

Supply of a highland town — Warren 157 

Supply of a lowland town — North Haven 160 

Supply of a coast region — Branford Point 162 

Chapter VIII. Character of ground water of Connecticut 165 

Introduction 165 

Composition 166 

Determining character 166 

Hard and soft water 166 

Material taken into solution 167 

Normal distribution of chlorine 168 

Uses of water 169 

Water for domestic purposes 169 

Water for boilers ' 169 

Contamination 170 

Introduction 170 

Contamination by sewage 171 

Location of wells 171 

Depth and construction of wells 172 

Contamination in different rock types 172 

Contamination by sea water 174 

Relative value of water supply 175 

Analyses 175 

Chapter IX. Well construction in Connecticut 180 

Dug wells 180 

• Drilled wells 181 

Driven wells 182 

Chapter X. Springs 185 

Introduction 185 

Types of springs 185 

Seepage springs 185 

Stratum springs 186 

Fault and joint springs 187 

Temperature of spring waters 187 

Intermittent springs 188 

Mineral springs 189 

Volume of springs 189 

Use and production of spring waters 189 

Records of springs 189 

Bibliography 196 

Index 197 



ILLUSTRATIONS. 



y Pago. 

Plate I. /A, Vertical joints in granite; B, Horizontal joints in granite 60 

II. A, Joints in schist and metamorphosed diabase; B, Jointed and fissile 

/ schist 62 

III. A, Flowing well at Noroton Heights; B, Weathering due to ground 

r water in granite quarry 96 

IV. A, Vertical and horizontal joints in sandstone; B, Vertical and hori- 

/ zontal joints in trap 106 

V. Map of Connecticut, showing distribution of chlorine 168 

Figure 1. Map of Connecticut, showing physiographic provinces 13 

2. Diagram showing precipitation at Storrs 21 

3. Diagram showing precipitation at New Haven 22 

4. Diagram showing precipitation at Cream Hill 23 

5. Diagrammatic section illustrating seepage and growth of streams. . . 45 

6. Diagram illustrating artesian conditions where water does not rise to 

the surface 48 

7. Diagram showing formation of a stratum spring at an outcrop of an 

inclined impervious stratum 50 

8. Diagram illustrating the manner in which a spring may form at the 

contact of soil covering and the impervious rock below, when the 

soil is removed by erosion 50 

9. Diagram illustrating the manner of formation of a spring at the con- 

tact of a pervious formation and an impervious formation, when 
dissected 50 

10. Diagram illustrating effects of tides on water table 51 

11. Areas of limestone, sandstone, and crystalline rock water supplies of 

Connecticut 57 

12. Diagram illustrating the manner in which a well obtains water by 

cutting joints 61 

13. Sketch showing relation of water level to topography 71 

14. Logs of wells in crystalline rocks 77 

15. Diagram illustrating depression of water surface at point of leakage 

in sandstone 105 

16. Well logs showing influence of the Triassic black shale in determining 

water horizons 110 

17 . Well logs showing influence of the Triassic black shale in determining 

water horizons 112 

18. Fault zones in sandstone 114 

19. Section of the Connecticut Triassic as a synclinal basin — conditions 

favorable for artesian wells : 134 

20. Section of the Connecticut Triassic as a simple faulted monocline — 

conditions favorable for several small artesian basins 134 

21. Actual condition of Connecticut Triassic — faulting and jointing 

developed to such an extent as to preclude the possibility of large 
artesian basins 135 

22. Spring deriving its supply from joints and upward -sloping bedding 

planes 136 

7 



g ILLUSTRATIONS. 

Page. 
Fi»¥Re 23. Section of hilltop showing suitable catchment and reservoir condi- 
tions for a water supply to the rock fractures 141 

24. Section showing common relation of rock surface to overlying drift. 142 

25. Generalized section showing relation of rock to glacial drift 142 

26. Diagram of well at South Willington, showing water horizon at con- 

tact of till and stratified drift 143 

27. Map of Warren, showing location of wells 158 

28. Map of North Haven, showing location of wells 161 

29. Map of vicinity of Branford Point, showing location of wells 163 

30. Diagram illustrating the manner in which a well near the sea may 

be contaminated by salt water during the dry season 174 

31. Diagram illustrating conditions for intermittent spring 188 



INTRODUCTION. 



The study of the ground water of Connecticut, the results of which 
are presented in the following pages, was begun in 1903 with the collec- 
tion and examination of well and spring records and was continued 
at intervals during 1904 and 1905. During the autumn of 1905 
E. E. Ellis cooperated with the author in general investigations, and 
also made a study of the water in the crystalline rocks. In addition 
to the report on the special work assigned to him, Mr. Ellis has pre- 
pared parts of the chapters on occurrence and recovery of ground 
water, on character of water, and on well construction and has assisted 
in compiling data and in preparing illustrations. 

For information regarding chemical analyses thanks are due to 
Prof. Herbert E. Smith, of New Haven, and Mr. George H. Seyms, 
of Hartford. 

The writer wishes to express his great indebtedness to the well 
drillers of the State, who have freely given much valuable informa- 
tion regarding the occurrence and recovery of ground water. An 
unusual amount of carefully collected data has been furnished by 
Messrs. C. L. Grant, of Hartford; F. A. Champlin, of East Long- 
meadow, Mass.; C. L. Wright, of New Haven; R. L. Waterbury, of 
Glenbrook; H. B. King, of Hartford; and S. B. Hamilton, of Melrose, 

Mass. 

9 



UNDERGROUND WATER RESOURCES OF CONNECTICUT. 



By Herbert E. Gregory. 



CHAPTER I. 
GEOGRAPHY. 

TOPOGRAPHY. 

GENERAL RELATIONS. 

In its physiographic relations Connecticut is part of the New 
England plateau, which is characterized by complex groupings of 
hills composed of igneous and metamorphic rocks; by a few broad 
valleys cut in softer and less resistant rock material; and by many 
narrow valleys intrenched in the plateau, and in the main occupied 
by important watercourses. Other topographic features date from 
the advent of the great ice sheet of Pleistocene or " Glacial" time, 
which completely remodeled the New England landscape, accentu- 
ating or subduing the previous topography and originating new land 
forms. The plateau is, however, so dissected as to present the appear- 
ance of a region of hills, valleys, and narrow plains, differing in extent 
and outline. 

Viewed as a whole, the surface of Connecticut is a plateau sloping 
gradually from Cornwall and Goshen southeastward to the Sound. 
There are no high precipitous mountains or sharply cut canyons, but 
nevertheless the topography is rugged beyond the average of regions 
of slight elevation and great physiographic age. High cliffs and rock 
walls are exhibited in the trap of the central lowland and along cer- 
tain streams in the highlands, but the hilltops are on the whole 
rounded and the ridges show a tendency to a north-south alignment. 
The character of the relief and the prevalence of a north-south 
arrangement of the hills are well shown by the railroad map of the 
State, some of the lines occupying north-south valleys, and others 
crossing the ridges. The Highland division of the New York, New 
Haven and Hartford Railroad goes through the narrow defile at 
Bolton Notch, over the pass at Terryville, through the tunnel at 
Newtown, traversing 119 miles from Putnam to Danbury, though 

11 



12 UNDERGROUND WATER RESOURCES OF CONNECTICUT. 

the direct distance between these points is but 89 miles. Likewise 
the Central New England Railway, running westward from Hartford, 
requires 67 miles of track to reach the New York state line, a distance 
of 44 miles, and crosses the Highlands at Norfolk Summit, an eleva- 
tion of 1,298.58 feet. Norfolk, 2 miles farther west, with an elevation 
of 1,210.7 feet, is the highest railroad station in the State. The "Air 
Line" of the New York, New Haven and Hartford Railroad from 
Willimantic to Middletown is a short and direct east-west route, but 
its construction required expensive cuts and fills and bridges, and 
the grades are unsuitable for heavy traffic. On the other hand, the 
Northampton division of the same railroad, extending northward from 
New Haven to the Massachusetts line, is but 1 mile longer than the 
distance as measured on a map; and the Hartford division, which 
traverses the lowland from New Haven to Thompsonville, exceeds a 
direct line by only 2 miles. Even in the heart of the highland areas, 
the Central Vermont Railway crosses the State in a north-south 
direction along the winding courses of She tucket and Willimantic 
rivers with but 8 miles of track more than the direct distance. In 
fact, if a railroad were to be constructed from Putnam in a straight 
line westward across the State the difficulties of operation would be 
scarcely less than those encountered in truly mountainous districts. 

PHYSIOGRAPHIC FEATURES. 

Physiographically, Connecticut may be divided into the western 
highland, occupying that portion of the State west of a line running 
from New Haven to North Granby; the eastern highland, between 
Rhode Island and a line through Somers, Rockville, Glastonbury, 
Middletown, and Branford; and the central lowland, occupying the 
remainder of the area. (See fig. 1.) These three provinces have 
characteristic groupings of topographic features which have a direct 
bearing on the water resources of the State and which have been the 
controlling factors in its settlement and industrial history. 

THE HIGHLANDS. 

Western highland. — The western highland increases in elevation 
from the Sound northward and contains areas of considerable size 
over 1,000 feet in height. In Barkhamsted the plateau reaches an 
elevation of 1,400 feet, in Colebrook of 1,500 feet, in Goshen and 
Cornwall of 1,600 feet, and in Norfolk of 1,700 feet, and it culminates 
in Bear Mountain, Salisbury, at 2,355 feet. The plateau terminates 
abruptly on the east and at certain points, as Compounce Pond, the 
rise from the lowland is precipitous. Differences in elevation and in 
character and prominence of rock outcrops and the presence of 
numerous valleys of widely varying depth, width, and extent, give 
the highlands an appearance of great complexity. They are not, 



GEOGRAPHY. 



13 



however, a " region of disorderly hills," but have been controlled in 
topographic development by geologic forces whose influence was felt 
throughout southern New England. It was noticed by Percival a 
that the highlands "may both be regarded as extensive plateaus/' 




which "present, when viewed from an elevated point on their surface, 
the appearance of a general level, with a rolling or undulating out- 
line, over which the view often extends to a very great distance, 
interrupted only by isolated summits or ridges, usually of small ex- 



a Percival, J. G., Report on the geology of Connecticut, 1842, p. 477. 



14 UNDERGROUND WATER RESOURCES OF CONNECTICUT. 

tent." A good view from any exposed point in the highlands con- 
firms this impression of a plateau surface rather than a confused 
mingling of hills. As concisely stated by Professor Rice: a ".If we 
should imagine a sheet of pasteboard resting upon the summits of 
the highest elevations of Litchfield County and sloping southeastward 
in an inclined plane, that imaginary sheet of pasteboard would rest 
on nearly all the summits of both the eastern and the western high- 
lands." Certain mountains project above the general level of the 
plateau and many valleys are cut below it. Owing to the resistant 
character of the rocks composing them, Great Hill, Cobalt, 700 feet; 
Lantern Hill, Mystic, 520 feet; Mount Horr, Canton, 880 feet; Mount 
Prospect, Litchfield, 1,365 feet; Mount Haystack, Norfolk, 1,680 feet; 
and other points stand out as prominent landmarks above the general 
surface at their base. 

The origin of the highland plateau is revealed by an examination 
of the composition and structure of its basement rock, which clearly 
shows that the surface as it now exists is not the result of accumu- 
lation of sediments of great thickness. The bed rock of the high- 
lands is not sedimentary nor horizontal, but is metamorphic and 
igneous rock which has been folded and twisted and injected, and 
which could have been formed only at a great depth below the earth's 
surface. Mountains have been removed from western and eastern 
Connecticut, and the remaining rocks, with their bewildering com- 
plexity of structure, are but the stumps of old land masses which 
have been sawed horizontally across by the agents of erosion. If the 
present valleys were filled and a few projecting hills cut down the 
conditions of Cretaceous time would be restored and the highlands 
would appear as a plain — the result of long-continued, ceaseless 
activity on the part of rain, frost, and streams. 

Eastern highland. — The counterpart of the western highland is 
found in the eastern part of the State, but the eastern highland rep- 
resents much less contrast in relief and does not attain such altitudes. 
Practically all the prominent Hills and ridges in this province are 
under 700 feet in height, and only in the towns along the Massachu- 
setts line is an elevation of 1,000 feet attained, the culminating points 
being Rattlesnake Hill, Somers, 1,080 feet; Bald Mountain, Somers, 
1,120 feet; Soapstone Mountain, Somers, 1,061 feet; Hedgehog Hill, 
Stafford, 1,180 feet; Bald Hill, Union, 1,286 feet; Stickney Hill, 
Union, 1,220 feet; Lead Mine Hill, Union, 1,140 feet; Snow Hill, 
Ashford, 1,213 feet; and Hatchet Hill, Woodstock, 1,040 feet. 

Valleys in the highlands. — The valleys in the highlands are those 
which have been cut since the formation of the peneplain (see p. 33), 
and their character is determined by the rocks which they traverse 
and by the age and size of the streams which have occupied them. 

a Rice, W. N., and Gregory, H. E., Manual of Connecticut geology, 1906, p. 20. 



GEOGKAPHY. 15 

The western highland is traversed by two well-marked valleys — those 
of Housatonic-Norwalk and Naugatuck-Still rivers, which inclose a 
rectangle of the highest land within the State. These valleys are 
intrenched 400 to 600 feet in the plateau and, although not occupied 
by continuous streams, they constitute the only feasible lines of com- 
munication between the northern and southern parts of the western 
highland. The two valleys are connected by the gorgelike trough of 
the Housatonic, which cuts through the rock ridges with a fall of 10 
feet per mile. The Housatonic Valley at Danbury and at Canaan and 
the Naugatuck-Still Valley at Winsted widen into undulating plains. 
The Farmington Valley through the highlands is a gorge less than 
1,000 feet in width below Riverton, and still narrower at Hartland, 
where it is sunk 600 feet below the plateau, and at Satans Kingdom 
it is barely 200 feet wide. Nearly all the minor streams of the western 
highland are intrenched in fairly narrow valleys, except the Pom- 
peraug, which meanders freely over a miniature lowland on Triassic 
sediments. 

In the eastern highland the valleys entering the lowland are mostly 
short and narrow and of high gradient. One important valley gorge, 
now occupied by Connecticut River, leads from the central lowland 
southeastward to the Sound. The Thames Valley is a fiord to Nor- 
wich. Its eastern branch, the Quinnebaug, is a steep-walled valley 
to South Canterbury, above which it widens into a plain through 
Plainfield, Killingly, and Putnam. The Shetucket-Willimantic Val- 
ley is broad and open through most of its course, as are also its 
northern branches, which divide the highland into segments. 

The floor of the highland valleys is bed rock, till, or stratified drift, 
no stream having entirely removed the cover of glacial drift along its 
path. Some streams, in fact, like the east branch of the Farmington, 
flow through almost their entire courses without reaching bed rock. 

A glance at the topographic map shows that the chief valleys trend 
either north and south or northwest and southeast. For example, 
the Housatonic from Gaylordsville to Derby, the Connecticut from 
Middletown to Lyme, the Farmington from Colebrook to Farming- 
ton, and the Shetucket and many valleys of lesser size are alike in 
their north-south alignment. The upper Connecticut, the Willi- 
mantic, the Mount Hope, Little River (Windham County), and sev- 
eral minor streams trend in a common direction. There is nothing 
in the nature of the rock which accounts for the common alignment 
of these two groups of valleys and, if only present geologic conditions 
are taken into account, the southeasterly courses of the Housatonic 
below New Milford and of the Connecticut below Middletown are 
anomalous, for these rivers leave well-developed valleys of limestone 
and sandstone and cut their way through the most resistant gneisses 
and schists. There seems no escape from the conclusion that they 



16 UNDERGROUND WATER RESOURCES OF CONNECTICUT. 

established their courses on an ancient coastal plain which sloped to 
the southeast. As a result of the uplift and consequent erosion, the 
strata forming the plain have been removed, but the streams have 
maintained their original directions, cutting valleys deep into the 
rocks of the plateau. (See p. 19.) 

It has been shown by Hobbs a that the main valley lines of the 
State coincide in direction with five prominent systems of joints and 
faults and there is doubtless some genetic relationship between the 
joints and the trend of trough lines. 

CENTRAL LOWLAND. 

Extent and character. — The central lowland differs from the high- 
lands in altitude, character of bed rock, drainage, and types of hills 
and valleys. In extent it is coincident with the larger of the two 
areas of Triassic sediments within the State. Except in the lava 
ridges, the altitude of the lowland averages about 100 feet and only 
in the region south of Middletown does it exceed 500 feet. As viewed 
from the highlands — for instance, at Bald Mountain, Somers, or Box 
Mountain, Bolton, from Bristol, or from the ridges near Canton — the 
lowland surface appears as a plain from which rise ridges of lava. 
The edges of the highland areas, as viewed from the lowland, present 
abrupt walls, as seen in Southington and Somers, or steeply rising- 
slopes. In Glastonbury, Middletown, and Branford the lowland 
merges imperceptibly into the highland. 

Lava ridges. — The most marked topographic feature of the lowland 
and, in fact, of the entire State, is the series of basalt ridges which 
extend from North Granby to East Haven. As far south as Meriden 
the ridges form a continuous line of elevation broken only by gaps 
and passes. From the Hanging Hills this ridge line passes by a series 
of rough steps to Beseck Mountain and thence continues southward 
as Totoket and Saltonstall ridges. 

The most prominent parts of this ridge system are Peak Mountain, 
665 feet; Talcott 'Range, the highest point of which is 960 feet; 
Rattlesnake Mountain, 750 feet; Ragged Mountain, 754 feet; Hang- 
ing Hills, 700 to 1,000 feet; Lamentation Mountains, 654 and 725 
feet; Higby Mountain, 920 feet; Beseck Mountain, 840 feet; Pista- 
paug Mountain, 640 feet; Totoket Mountain, 780 feet; Saltonstall 
Ridge, 240-245 feet. The culminating point is West Peak, Meriden, 
1,007 feet, which is fully up to the level of the highlands and furnishes 
a magnificent view of the Farmington-Quinnipiac Valley and the 
Wolcott Plateau beyond. The ridge of lava faces westward as a 
bold escarpment, but slopes gently to the east, where it merges into 
the lowland floor. Breaks through the ridge formed by streams or 
by faults furnish passes for railroads at Tariffville, New Britain, 
Meriden, and Baileyville. 

a Hobbs, W. H., River system of Connecticut: Jour. Geology, vol. 9, 1901, pp. 469-485. 



GEOGRAPHY. 17 

Farmington and Connecticut valley lowlands. — The central ridge of 
lava forms a conspicuous and effective line of demarkation between 
the two parts of the central lowland — the Connecticut Valley and 
the Farmington-Quinnipiac Valley. 

The Connecticut Valley area from Thompsonville to Middletown 
is practically a plain of drift and till 5 to 10 miles in width and with 
differences in elevation of less than 200 feet. South and west of 
Middletown the valley area passes by gradual stages into the eastern 
highland and the central ridges. The elevations in the Connecticut 
Valley lowland are drumlins and other glacial deposits and till- 
covered sandstone knolls. The streams tributary to the Connecticut 
are ditches cut into glacial deposits. The Scantic, Podunk, Hock- 
anum, and others seldom reveal rock floor; Stony Brook (Sufneld) 
is the type of a few streams which have cut through the drift to the 
sandstone below. 

The Farmington-Quinnipiac Valley extends from New Haven 
northward across the State and is bounded on the west by the steep 
edge of the western highland and on the east by the broken wall of 
the central ridge. It is occupied by three rivers — the Farmington, 
Quinnipiac, and Mill (New Haven) — all of which, in common with 
their tributaries, flow almost entirely on glacial drift. From the 
floor of the Farmington-Quinnipiac Valley rise a number of trap 
hills which break the continuity of the plain. The most prominent 
of these are the Barndoor Hills, 600 to 700 feet; Mount Carmel, 737 
feet; West Rock, 405 feet; and East Rock, 359 feet. The level, 
drift-filled floor of this valley lowland, together with the slight 
difference in elevation between New Haven and the Congamuck 
ponds, made the valley an attractive route for a canal, which was 
built in 1829 and was later succeeded by the Northampton Railroad. 

COAST LINE. 

The coast line is much indented and presents a multitude of bays, 
headlands, points, inlets, and marshes. Rock islands occur in 
groups, as at Norwalk and off Branford, or are scattered irregularly 
along the shore. Westward-moving tides and currents have built 
innumerable beaches, bars, and spits along the coast, thus greatly 
modifying its original outline. The character of the coast is due to 
the fact that the land has been depressed, allowing the sea water 
to enter the old valley now constituting Long Island Sound and to 
drown the irregular southern edge of the denuded peneplain. 

DRAINAGE. 

Connecticut is drained largely by streams which rise within its 
borders. Only two streams of large size — the Connecticut and the 
Housatonic — carry water from lands beyond the State, and the 
463— irr 232—09 2 



18 UNDEEGKOUND WATEK RESOURCES OF CONNECTICUT. 

Massachusetts section of the Housatonic serves but a small area. 
The three main river systems are the Housatonic, the Connecticut, 
and the Thames, which drain, respectively, 1,272, 1,443, and 1,164 
square miles, or altogether 78 per cent of the surface. 

Of the streams which enter Long Island Sound independently — 
the Byram, Mianus, Mill (Stamford), Norwalk, Saugatuck, Mill 
(Fairfield), Poquonock, Wopowaug, West, Mill (New Haven), Quin- 
nipiac, Hammonassett, Niantic, Mystic, Pawcatuck, and certain 
smaller ones — the Quinnipiac, 35 miles long, is the only one over 20 
miles in length, and all have small drainage basins. 

In a number of places the divides between adjoining drainage 
areas are ill defined and a few stream systems coalesce. Thus the 
limestone valley extending from New Preston to Bedford, N. Y., an 
area of slight relief, is drained by five streams that have independent 
outlets to the sea — the Mianus, Norwalk, Saugatuck, Housatonic, 
and the Croton (a tributary to the Hudson). Likewise the Quine- 
baug, Bigelow Brook, the Natchaug, and the Shetucket together 
form a closed ring of water surrounding ten towns in the north- 
eastern part of the State. 

The lower ends of the streams entering the Sound are drowned, 
and the tides, 4 to 7 feet in height, reach up these streams to a 
greater or less distance. For example, the Connecticut is tidal to 
Hartford, 44 miles; the Thames to Norwich, 15 miles; the Housatonic 
to Derby, 1 1 miles ; the Quinnipiac to Quinnipiac, 1 miles. Accord- 
ingly the lower reaches of the streams along the coast line are of 
no value for water supplies. 

The streams of the highlands have steep gradients and their flow 
is interrupted by numerous waterfalls and rapids. This is particu- 
larly true of the streams entering the central lowland and of small 
streams in general. Thus, the Farmington from Cold Spring, Mass., 
to New Hartford falls 29.76 feet to the mile; the Shepaug descends 
at the rate of 30.5 feet to the mile, making one drop, at Bantam, of 
108 feet in less than three-quarters of a mile; Moodus River falls 
350 feet in 2 miles. Even the Housatonic falls 3.5 feet to the mile 
from Stratford to Shepaug; 10.2 feet to the mile from Shepaug to a 
station 1.8 miles above Cornwall bridge; 19.4 feet to the mile from 
this last-named point to Falls Village; and 9.2 feet to the mile from 
Falls Village to Ashley Falls, one-half mile north of the Connecticut 
boundary line. The descent of the Housatonic is accomplished by 
stretches of gravelly rapids alternating with reaches of relatively 
quiet water, but at New Milford, Bulls Bridge, and Falls Village 
there is an abrupt drop over rock ledges. At Falls Village the com- 
bined height of the falls is about 100 feet. a 

a Porter, Dwight, Report on water power of the region tributary to Long Island Sound : Tenth 
Census, vol. 16, 1885. 



GEOGRAPHY. 19 

The streams of the lowland area have slight fall and in some 
places are aggrading their valle} T s. The Scantic, Hockanum, Farm- 
ington, Pequabuck, Mill (New Haven), Farm, and others are sluggish 
streams which meander freely. The Quinnipiac, with a drainage 
basin of 156 square miles and a length of 35 miles, falls 5 feet to the 
mile from Plantsville to New Haven. The Connecticut has a fall of 
only 0.6 foot to the mile from Enfield Rapids to Hartford; and from 
Hartford to Say brook no fall whatever. The entire fall of Connecticut 
River in crossing the State in the lowlands is about 30 feet, as com- 
pared with the fall of Housatonic and Willimantic-Shetucket-Thames 
rivers in the highlands — 650 and 600 feet, respectively. There are, 
however, many waterfalls and rapids of considerable size and great 
picturesqueness along the streams of the central lowland. 

Lakes, swamps, and salt marshes occupy 145 square miles of the 
State, the topographic map showing 1,026 lakes, the largest of which 
is Lake Bantam, with an area of 1.56 square miles, or 999 acres. 
Swamps are even more abundant than lakes, and if the smaller, 
partly drained ones are taken into account they number several 
thousand. The importance of these water bodies is evident. They 
furnish supplies for cities, add greatly to the beauty of the landscape, 
and are particularly effective in controlling the drainage, serving as 
reservoirs to retard the escape of rainfall and thus preventing destruc- 
tive floods. 

A glance at the map of Connecticut will show that the drainage is 
to the southeast and that the streams flow in accord with the general 
slope of the plateau, but even a superficial glance reveals the fact 
that not all the larger streams are in the prominent valleys and that 
many occupy positions where the bed rock is unfavorable for valley 
development. The Connecticut, for instance, instead of following the 
sandstone to New Haven, leaves the lowland at Middletown and turns 
abruptly into the crystalline rocks of the highlands, through which 
it has cut a deep gorge. Likewise the Housatonic, which follows a 
limestone valley down to Still River, turns southeastward across 
rugged crystalline rocks instead of continuing in the valley indicated 
by rock structure. The same is true of a number of smaller streams. 
Anomalies of another class are illustrated in the arrangement of cer- 
tain smaller streams whose direction and grade, as well as character 
of valley, are entirely out of accord with the present topography. 
For example, Still River at New Milford and a stream of the same 
name at Winsted flow in a direction contrary to the slope of their 
valleys and enter their master streams by dropping over falls. The 
Farmington follows the slope of the ancient peneplain from Colebrook 
River to Farmington, there turns northward, cuts through a trap 
ridge at TarifTville, and finally reaches the Sound after flowing a dis- 



20 UNDEEGKOUND WATEK EESOUKCES OF CONNECTICUT. 

tance of 103 miles instead of the necessary 64 miles to New Haven or 
74 miles by way of the Connecticut at Middle town. 

Without going further into detail, it may be stated that the char- 
acteristic features of the present drainage are due to two main causes. 
First, the streams were established on a peneplain during Cretaceous 
time and followed the slope to the south and southeast regardless of 
the character of the underlying rocks. The Connecticut, Housatonic, 
and other streams have maintained this inherited position. Second, 
the entire drainage of the State has been modified by glaciation. The 
courses of some streams have been reversed, other streams have been 
cut in two, and still others have been entirely obliterated or are rep- 
resented by lakes and swamps. In fact a widespread rearrangement 
of streams as to direction and grade has been brought about. 

FORESTS. 

The distribution of forests in the State follows closely the subdivi- 
sions into highland and lowland areas. The eastern and western high- 
lands are largely forest covered, and in recent years the forest areas 
have been encroaching on the agricultural districts. In the central 
lowland the soil, transportation facilities, and nearness to market 
render agriculture more remunerative, and the forests are represented 
by small, scattered wood lots. Taken as a whole, Connecticut is a 
well-timbered country, 39 per cent of its area being covered with 
trees. 

CLIMATE. 

METEOROLOGICAL DATA, a 

Sixteen climatological stations are maintained by the United States 
Weather Bureau in Connecticut — at Bridgeport, Canton, Colchester, 
Cream Hill, Danielson, Hartford, Hawleyville, New Haven, New Lon- 
don, North Grosvenordale, Norwalk, Southington, Storrs, Torrington, 
Voluntown, and Waterbury. In Falls Village, Middletown, South 
Manchester, Wallingford, and West Simsbury record is kept of rainfall 
and temperature. 

The following tables and figures 2, 3, and 4 present data collected 
at three selected stations; one in the eastern highland — Storrs, at an 
elevation of 640 feet ; one in the central lowland — New Haven, eleva- 
tion 25 feet; and the third in the western highland — Cream Hill, 
elevation 1,300 feet. The tables for the New Haven station give 
records of rainfall, temperature, humidity, and wind velocity, which 
are controlling factors in ground-water supply. 

a From United States Weather Bureau records. 



GEOGRAPHY. 



21 



Precipitation (in inches) at Storrs, 1897-1906. 
[Elevation, 640 feet.] 



Year. 


Jan. 


Feb. 


Mar. 


Apr. 


May. 


June. 


July. 


Aug. 


Sept. 


Oct. 


Nov. 


Dee. 


Annual. 


1897 


3.84 


3.40 


3. 66 


2.37 


4.44 


2.79 


12 24 


5 23 


1 39 


0.92 
6.18 


7.14 
6.11 


5.61 
1.96 


53.03 
51.13 


189S 


4.70 


4.03 


3.00 


4.44 


3.81 


2.48 


6.24 


5.87 


2.22 


1899 


3.70 


3.97 


6.30 


.2.20 


1.27 


3.72 


5. 55 


3.27 


3.31 


1.54 


2.10 


2.14 


39.13 


1900 


3.42 


7.31 


6.73 


2.67 


4.91 


4.32 


2.76 


2.03 


2.27 


3.00 


6.79 


2.22 


48.43 


1901 


2.17 


1.05 


7.18 


9.51 


6.30 


1.96 


5. 54 


7.58 


4.33 


1.97 


3.04 


9.55 


60.18 


1902 


2.53 


5.11 


6.35 


3.88 


1.59 


3.24 


7.48 


2.17 


7.05 


5.68 


1.10 


5.86 


53.75 


1903 


3.79 


5.18 


7.09 


2.81 


.50 


9.24 


4.56 


4.52 


1.81 


2.79 


1.95 


4.27 


48.51 


1904 


4.55 


2.80 


3.31 


6.40 


1.96 


2.53 


1.85 


6.00 


4.71 


2.19 


1.47 


2.42 


40.19 


1905 


3.57 


1.21 


3.45 


2.87 


.90 


4.53 


1.77 


2.63 


5.79 


2.57 


2.73 


4.12 


36.14 


190G 


3.10 


2.08 


5.46 


4.40 


5.87 


2.18 


5.03 


2.16 


2.05 


4.85 


2.39 


2.80 


43.63 


Mean 


3.54 


3.07 


5.25 


4.16 


3.15 


3.70 


5.30 


4.15 


3.49 


3.17 


3.48 


4.10 


47.16 




Winter. 


Spring. 


Summer. 


Fall. 


Mean for season 


11. 31 


i? kr 


13 


.15 


10.14 













) 



20 



GO 



70 



1890 
1891 
1892 
1893 
1894 
1895 
1896 
1897 
1898 
1899 
1900 
1901 
1902 
1903 
1904 
1905 
1906 



Jan. 
Feb. 
Mar. 
Apr. 
May 
June 
July 
Aug. 
Sept. 
Oct. 
Nov. 
Dec. 



Winter 
Spring 
Summer 
Fall 





























53.03 

— 51.13— 

39.13 

48.43 

60.18 

■ 53.75— 

— 48.51 






Annual pr 


ecipitation, 1 


890 to 1906 




36.14 

43,63 


_^_ 














• 














^5_' 














5» 














Si 














^~ 




























^j* 














^* 














^~ 














■n 
































Mean month 


ly precipitati 


>n, 1897 to IS 


0t> 










^^^^ 








Mean annua 


precipitation, 1897 to 1906 
































■B — 12.56- 




























Mean season 


al precipitati 


on, 1897 to li 


)06 





Figure 2.— Diagram showing precipitation, in inches, at Storrs. 



22 



UNDERGROUND WATER RESOURCES OF CONNECTICUT. 



Precipitation (in inches) at New Haven, 1897-1906. 
[Elevation, 25 feet.] 



Year. 


Jan. 


Feb. 


Mar. 


Apr. 


May. 


June. 


July. 


Aug. 


Sept. 


Oct. 


Nov. 


Dec. 


Annual. 


1897 


3.85 
4.90 
4.33 
3.60 
1.38 
1.83 
3.17 
2.78 
4.14 
3.20 


2.00 
4.55 
3.39 
6.39 
.54 
3.58 
3.98 
2.52 
2.06 
2.45 


3.66 
2.54 
7.28 
4.21 
5.80 
4.63 
5.09 
3.28 
2.96 
5.67 


2.44 
4.43 
1.79 
1.95 
9.03 
3.40 
2.61 
6.64 
3.42 
4.48 


5.03 
8.03 
5.52 
3.30 
6.38 
1.61 
.31 
2.94 
1.18 
4.75 


2.47 
.21 
2.59 
1.79 
.25 
4.35 
7.41 
2.46 
5.87 
5.14 


10.63 
5.03 

4.17 
2.28 
4.40 
3.26 
2.17 
2.08 
2.86 
5.62 


6.81 
6.65 
.65 
.90 
6.92 
2.14 
6.96 
6.27 
7.20 
1.13 


2.42 
2.30 
3.33 
2.10 
5.70 
5.84 
2.20 
4.96 
5.07 
4.82 


1.25 
7.22 
1.78 
2.03 
2.95 
6.41 
2.94 
2.21 
2.21 
7.44 


5.72 
5.69 
1.89 
4.14 
1.61 
.79 
1.85 
1.95 
1.53 
2.42 


5.61 
2.11 
1.56 
2.14 
7.65 
6.49 
2.53 
3.64 
4.83 
4.18 


57.80 
53 66 


1898 


1899 


35 28 


1900... 


34.83 
68.81 
44.33 
41 22 


1901 . . . 


1902... 


1903 


1904 


41 73 


1905 


43 33 


1906 


51 30 






Mean 


3.32 


3.15 


4.51 


4.02 


3.91 


3.25 


4.25 


4.56 


3.87 


3.64 


2.76 


4.07 


45.31 





Winter. 


Spring. 


Summer. 


Fall. 


Mean for season 


10.54 


12.44 


12.06 


10.27 







10 



20 



30 



1890 
1891 
1892 
1893 
1894 
1895 
1896 
1897 
1898 
1899 
1900 
1901 
1902 
1903 
1904 
1905 
1906 




























37.78— 














37.74 — 

35.96 — 

38.39— 

57.80 — 

53.66 — 














34.83 — 

— 44.33 — 














41.73 — 






Annual pr 


ecipitation, 1 


390 to 1906 




51.30 




















Mean annual precipitation, 1897 to 190 


5 




Jan. 
Feb. 
Mar. 
Apr. 
May 
June 
July 
Aug. 
Sept. 
Oct. 
Nov. 
Dec. 




■ | 






































































































































































Mean month 


y precipitatk 


>n, 1897 to 19 


06 




Winter 
Spring 




■ i r\ r a 














■-12.44 — 












Fall 




1 10.27 — 


Mean season 


al precipitatic 


>n, 1897 to 19 


06 





68.81 



Figure 3.— Diagram showing precipitation, in inches, at New Haven. 



GEOGRAPHY. 



23 



The average precipitation at New Haven for thirty years ending 
December 31, 1903, was as follows: 



Average precipitation at New Haven for thirty years ending December .11, 1903. 



Inches. 

January 4. 03 

February 4. 02 

March 4. 51 



April. 
May.. 
June. 
July.. 



August 4 

September 3. 66 

October 4. 28 



Indies. 

November 3. 73 

December 3. 79 



Annual 47. 97 



Mean for season : 

Winter 11. 84 

Spring 11.67 

Summer 12. 79 

Fall 11.67 



1890 
1891 
1892 
1893 
1894 
1895 
1896 
1897 
1898 
1899 
1900 
1901 
1902 
1903 
1904 
1905 
1906 



Jan. 
Feb. 
Mar. 
Apr. 
May 
June 
July 
Aug. 
Sept. 
Oct. 
Nov 
Dec. 



20 



30 



40 



50 



60 



70 



Winter 
Spring 

Summei 
Fall 



























































































































































56.94— 














56.85— 












48.20— 


















Annual precipitation, 1 


897 to 1906 








n />i 












JJ 




























5? 














5E 














"*"* 














- 














^■m 














— — 














.-^~ 














■ : ^m 














"" 


















Mean month 


ly precipitati 


on, 1897 to 1 


)06 








^^^^^^^^ 










Mean annual precipitation, 1897 to 19 


16 






■ 11.42 

■ 11.92 


































BHMI i - f < ft- r > 














■ 11.20 


Mean season 


al precipitati 


on, 1897 - 19 
. . 


)6 





Figure 4. — Diagram showing precipitation, in inches, at Cream Hill. 



24 



UNDERGROUND WATER RESOURCES OF CONNECTICUT. 



Precipitation (in inches) at Cream Hill, 1897-1906. 
[Elevation, 1,300 feet.] 



Year. 


Jan. 


Feb. 


Mar. 


Apr. 


May. 


June. 


July. 


Aug. 


Sept. 


Oct. 


Nov. 


Dec. 


Annual. 


1897 


3.54 
3.52 
3.47 
2.82 
1.52 
3.26 
3.93 
4.69 
6.91 
2.41 


2.21 
3.68 
4.13 
5.97 
.84 
4.90 
4.97 
3.13 
1.68 
2.55 


2.09 
2.37 
5.84 
3.84 
7.33 
4.68 
4.94 
4.46 
3.12 
4.06 


3.16 
4.31 
1.47 
1.95 
6.83 
4.76 
3.20 
3.12 
2.74 
3.67 


4.22 
6.70 
1.75 
5.13 
6.90 
2.99 
1.39 
4.28 
2.35 
5.61 


5.15 
2.87 
3.39 
4.42 
1.69 
5.06 
9.74 
3.52 
3.90 
5.60 


9.71 
1.79 
6.70 
6.09 
4.57 
9.40 
4.07 
6.15 
5.83 
6.47 


5.28 
6.77 
1.11 
2.18 
6.97 
4.70 
5.65 
3.89 
4.71 
3.14 


2.85 
4.25 
4.21 
1.75 
4.52 
7.83 
2.85 
7.90 
6.83 
3.58 


1.04 
3.35 
1.67 
2.73 
4.37 
5.42 
6.39 
2.71 
2.90 
4.02 


5.54 
6.46 
1.59 
5.29 
3.26 
.75 
3.10 
1.24 
2.19 
1.36 


4.53 
2.17 
2.21 
3.00 
8.14 
7.68 
6.65 
3.09 
2.59 
3.84 


49.32 
48.24 
37.54 
45 17 


1898 


1899 


1900 


1901 


56.94 
61.43 
56.85 
48.20 
45.75 
46 31 


1902 


1903 .... 


1904... 


1905 . . . 


1906 






Mean 


3.61 


3.41 


4.27 


3.52 


4.13 


4.53 


6.08 


4.44 


4.66 


3.46 


3.08 


4.39 


49.58 





"Winter. 


Spring. 


Summer'. 


Fall. 


Mean for season 


11.41 


11.92 


15.05 


11 20 







The average precipitation recorded at ten stations in Connecticut 
for the years 1893-1903 is as follows: 



Average precipitation at ten stations in Connecticut, 1893-1903. 



Inches. 

January 4. 28 

February 3. 94 

March 4. 23 

April.. 3.53 

May 4. 03 

June 2. 95 

July 4.42 

August 4. 30 

September 3. 34 

October 4. 04 



Inch* 



November 4. 48 

December 3. 44 



Annual 46. 



Mean for season : 

Winter 11. 66 

Spring 11. 79 

Summer 11. 67 

Fall 11.86 



Monthly and annual temperature (°F.) at Storrs, 1893-1903. 
[Elevation, 640 feet.] 





Jan. 


Feb. 


Mar. 


Apr. 


May. 


June. 


July. 


Aug ; 


Sept. 


Oct. 


Nov. 


Dec. 


Annual. 


Mean 


24 
28 
17 


24 

28 
19 


36 
43 
29 


46 
48 
42 


56 
60 
54 


64 
68 
59 


69 
72 
65 


68 
70 
62 


61 
64 
56 


50 
54 
45 


38 
44 
34 


30 
33 
23 


47 


Highest monthly 

mean 

Lowest monthly 










Winter. 


Spring. 


Summer. 


Fall. 


Mean for season 


C6 


46 


67 


50 





















GEOGRAPHY. 

Monthly and annual temperature (°F.) at New Haven, 1873-1903. 
[Elevation, 25 feet.] 



25 





Jan. 


Feb. 


Mar. 


Apr. 


May. 


June. 


July. 


Aug. 


Sept. 


Oct. 


Nov. 


Dec. 


Annual. 




28 
37 
20 


29 
36 
20 


35 
45 

27 


46 
52 
39 


58 
64 
51 


66 
71 
61 


72 
76 
68 


70 
73 
65 


64 
70 
59 


53 

58 
48 


41 
47 
34 


32 
39 
26 


50 


Highest monthly 




Lowest monthly 
mean 











Winter. 


Spring. 


Summer. 


Fall. 




30 


46 


69 


53 







For thirty-one years the highest temperature at New Haven was 
100°, in September, 1881, and the lowest was 14° below zero, in Jan- 
uary, 1873. 

Monthly and annual temperature (°F.) at Cream Hill, 1897-1907. 
[Elevation, 1,300 feet.] 



Jan. 


Feb. 


Mar. 


Apr. 


May. 


June. July. Aug. Sept. 

1 i 


Oct. Nov. 


Dec. 


Annual. 


Mean 

Highest monthly 
mean 

Lowest monthly 


23.1 
30.2 
17.3 


22.0 
26.6 
16.3 


32.9 
39.2 
26.0 


44.0 
45.4 
40.6 


56.0 
59.0 
53.8 


64.0 
66.0 
60.0 


69.4 
72.1 
66.1 


66.6 
70.6 
61.2 


61.4 
64.6 
58.6 


51.0 
54.6 
47.6 


36.7 
42.4 
32.2 


26.0 
29.7 
21.4 


16 









Winter. 


Spring. 


Summer. 


Fall. 




23.7 


43.3 


66.7 


49.7 







Mean relative humidity (per cent) at New Haven, 1901-1906. 



Year. 


Jan. Feb. 


Mar. 


Apr. 


May. 


June. 


July. 


Aug. 


Sept. 


Oct. 


Nov. 


Dec. 


Annual. 


1901 

1902 

1903 

1904 

1905 

1906 

Mean 


72 62 

70 69 

71 i 73 

72 ; 67 
68 | 63 
74 1 69 


74 
76 
78 
72 
71 
69 


77 
69 
65 
70 
66 
63 


79 
65 
65 
69 
71 
70 


70 
71 
82 
75 

74 
75 


80 

77 
73 
75 
76 
82 


83 
75 
79 

77 
81 
81 


80 
84 
79 
80 
80 
77 


76 
78 
79 
68 
71 
76 


67 
79 
68 
72 
67 
67 


77 
72 
69 
70 
70 
72 


75 
74 
73 

72 
72 
73 


71 


67 


73 


68 


70 


75 


77 


79 


80 


75 


70 


71 


73 





Winter. 


Spring. 


Summer. 


Fall. 




70 


70 


77 


75 







26 UNDERGROUND WATER RESOURCES OF CONNECTICUT. 

Mean relative humidity {per cent) at New Haven for fifteen years ending in 190S. 



Time. 


Jan. 


Feb. 


Mar. 


Apr. 


May. 


June. 


July. 


Aug. 


Sept. 


Oct. 


Nov. 


Dec. 


Annual. 




74 
71 


73 

72 


71 
69 


74 
74 


77 
76 


78 
78 


80 

78 


80 
80 


78 
76 


76 

74 


75 

72 


76 

72 


76 




74 







Average velocity {miles per hour) and direction of wind at New Haven, 1900-1905. 



Year. 


Jan. 


Feb. 


Mar. 


Apr. 


May. 


June. 


July. 


Aug. 


Sept. 


Oct. 


Nov. 


Dec. 


Annual. 


1900— Vel 

Dir 

1901— Vel 

Dir 

1902— Vel 

Dir 

1903— Vel 

Dir 

1904— Vel 

Dir 

1905— Vel 

Dir 


10.1 

N. 

9.9 

N. 

9.8 
NW. 
10.2 

N. 
10.3 
. N. 
11.2 

N. 


11.3 

W. 
11.2 
NW. 
13.0 

W. 
10.0 

W. 
10.6 

N. 
10.7 

W. 


10.6 

N. 
11.0 

NW. 
11.4 

N. 

9.5 
NE. 
10.1 
NW. 

8.2 

N. 


9.5 

N. 
13.3 

NE. 
9.9 

S. 

11.7 

N. 

10.7 
NW. 

10.1 
NW. 


9.1 

SW. 

9.8 

S. 

9.2 
SW. 

8.0 

S. 

8.2 

S. 

9.0 

S. 


8.8 
SW. 

7.8 

S. 

8.4 
SW. 

8.5 
NE. 

8.2 

S. 

7.8 

S. 


8.1 

SW. 

6.8 

SW. 

7.2 
SW. 

7.8 
SW. 

8.2 

S. 

7.8 

S. 


7.1 

SW. 
6.9 

S. 

7.2 
NW. 

7.3 
N. 

7.7 

S. 

7.9 
SW. 


8.1 

SW. 

7.1 

SW. 

8.4 
N. 

7.9 
SW. 

8.3 
N. 

8.3 
N. 


9.0 

N. 
8.6 
N. 
8.2 
.N 
11.3 
N. 
9.5 
N. 
8.6 
N. 


N. 

10.2 

NW. 
9.4 
N. 
8.4 
N. 
9.0 
NW. 
9.8 
NW. 


8.9 
SW. 
10.4 

N. 
10.8 

N. 
10.9 

W. 
10.7 

N. 

9.7 
SW. 


9.3 

S.W 

9.4 
N. 

9.4 
N. 

9.3 
N. 

9.3 
N. 

9.1 
N. 


Mean — Vel. 
Dir. 


10.3 

N. 


11.1 

w. 


10.1 

N. 


10.9 

NW. 


8.9 


8.3 
S. 


7. 7 
SW. 


7.4 
f S. 
\SW. 


8.0 

N. 
SW. 


9.2 


9.6 

l N. 
\NW. 


10.2 
}N. 


9.3 

N. 




Winter. 


Spring. 


Summer. 


Fall. 


Mean for season— Vel. 
Dir 




10.5 


10.0 

N.- 


7.8 
1 S. 

\sw. 


8.9 




N. 


1 N. 


















J 





Prevailing winds at New Haven for thirty-one years. 



January North. 

February North. 

March Northwest. 

April Northwest. 

May South. 

June South. 

July South. 



August South. 

September Southwest. 

October North. 

November North. 

December North. 

Annual North. 



SUMMARY. 

The foregoing tables indicate that the climate of Connecticut 
possesses both continental and oceanic features directly related to 
the highlands and to Long Island Sound. The winters are long and 
severe; the summers are short, beginning abruptly in June and pass- 
ing gradually into winter through autumn. Areas of high and low 
barometer which affect the weather of the State pass to the north 
down the St. Lawrence Valley, along the coast or directly across the 
State. Precipitation is uniformly abundant, and excessively dry 
years are unknown. There has been little change in the annual 
amount of rain for one hundred years, and the variation in seasonal 
amount is slight. (See figs. 2 to 4.) In fact, Connecticut may well 
serve as a type of uniform, evenly distributed rainfall of ample amount, 
in contrast with regions of seasonal rains and great annual variation. 



GEOGRAPHY. 



27 



The relation of temperature to ground-water problems is shown by 
the fact that percolation through sand is nearly twice as rapid at 
100° F. as at 50°, and, accordingly, the amount of rainfall absorbed 
by the ground is subject to large monthly and seasonal variation. 
The proportion of the total precipitation found in the ground at each 
month in the year is given in the following table : a 

Humidity of the ground. 



Month. 



January.. 
February 

March 

April 

May 

June 



Per cent at- 




1 foot. 


2 feet. 


3 feet. 


89 


95 


98 


76 


* 82 


88 1 


66 


72 


77 


54 


57 


65 


44 


45 


48 


32 


30 


30 



Month. 



July 

August — 
September 
October. . . 
November 
December. 



Per cent at- 



1 foot. 2 feet. 3 feet. 



SURFACE WATER SUPPLY. 



SOURCE AND CHARACTER. 



Of the water which falls as rain, a part is evaporated, another part 
enters the ground, and a third part goes directly into streams and is 
thus carried to the sea. The amount of water which is carried by streams 
has been approximately determined (see tables below), but there 
are no records of the amount evaporated, and accordingly the pro- 
portion of the rainfall absorbed by rocks and soils, and therefore 
available for springs and wells, is unknown. However, the amount 
evaporated is certainly small and, for rough calculations, the total 
rainfall may be divided into that which enters the ground (ground 
water) and that which is carried in streams (run-off). 

The relation of rainfall to run-off can not be stated definitely, 
because several factors of unknown value are included. The rate of 
precipitation, the topography of the surface, the texture of the soil, 
and the structure of the rocks are all to be considered. The presence 
of lakes and swamps along the stream's course and on its catchment 
area modify the surface run-off, and a large but unknown amount of 
ground water enters streams and lakes without reaching the surface. 
For instance, Lake Salt ons tall has a small drainage area — 4 square 
miles— and should receive 4,000,000 gallons of water a day. It 
actually receives, however, a much larger amount than can be 
accounted for by ordinary surface drainage and is presumably fed 
by subterranean springs and ground-water seepage. 

The presence of forests affects the relation of rainfall to run-off by 
increasing and regulating the flow of ground water. Deforestation 



a Sherman, Connecticut Almanac, 1885, p. 



28 



UNDERGROUND WATER RESOURCES OF CONNECTICUT. 



promotes evaporation, increases the run-off, and tends to produce 
seasons of flood. 

The general run-off of streams in the eastern part of the United 
States is 0.05 to 0.5 cubic foot per square mile per second, and streams 
tributary to Long Island Sound carry 17J to 27 £ inches of rainfall 
out of an annual total of 40 to 52 inches. a Variation in annual run- 
off is indicated by the record of Connecticut River, which shows the 
ratio of the run-off for a dry year to be 94 per cent of an average 
year's flow. 

QUANTITY AVAILABLE. 

The rivers whose discharge and run-off records are given below 
were chosen as typical Connecticut streams and fairly represent 
prevailing conditions. The She tucket is a stream of the eastern 
highland, established on gneiss and schist. The Connecticut drains 
the sandstone lowland, and the Housatonic flows for a large part of 
its course above Gaylordsville in a limestone valley. The run-off 
record is compared with the rainfall record of the meteorological 
station nearest the point where the discharge is measured. 

Discharge and run-off of Shetucket River at Willimantic April 4, 1904, to January 1, 1907. 



Date. 



1904. 

April 4 

May 

June 

July 

August 

September 

October 

November 

December 1-17, 28-31 

1905. 

March 

April 

May 

June 

November 

December 



Discbarge (second-feet). 



Maxi- 
mum. 



4,420 

2,350 
555 
345 
930 

2,930 
930 
990 

3,755 



3,805 
4,195 

706 
1,560 

555 
2,930 



Mini- 
mum. 



758 

385 

84 

84 

126 

66 

207 

150 

126 



275 
510 
275 
66 
207 
555 



Mean. 



1,784 
920 
326 
221 
373 
428 
396 
381 
831 



1,937 
1,254 
455 
565 
364 
902 



Run-off. 



Per 

square 
mile 
(second- 
feet). 



4.50 
2.32 
.823 
.558 
.942 
1.08 
1.00 
.962 
2.10 



4.89 
3.17 
1.15 
1.43 
.919 
2.28 



Depth 
(inches). 



1.20 
1.15 
1.07 
1.64 



5.64 
3.54 
1.33 
1.60 
1.03 
2.63 



Relation 

to rainfall 

(per 

cent). 



70.4 
136.7 
36.3 
34.8 
18.1 
25.5 
52.5 
72.8 
67.7 



163.5 
124.0 
147.8 
35.3 
37.7 
63.8 



Rainfall 
at Storrs 
(inches). 



6.40 
1.96 
2.53 
1.85 
6.00 
4.71 
2.19 
1.47 
2.42 



3.45 
2.87 
.90 
4.53 
2.73 
4.12 



a Porter, Census for 1880, vol. 16, pt. 1. 



GEOGRAPHY. 



29 



Discharge and run-off of Connecticut River at Hartford January 1, 1871, to Januan/ /, 

1886. 



[Drainage area, 10,234 square miles.] 





Discharge. 


Run-off. 




Date. 


Maxi- 
mum. 


Mini- 
mum. 


Mean. 


Per 

square 
mile 
(second- 
feet). 


Depth 
(inches). 


Relation 

to rainfall 

(per 

cent). 


Rainfall 

(inches). 


1871 


87,460 
98, 100 
109, 800 
134, 000 
90, 100 
120, 800 
128, 200 
89,350 
116,400 
65, 550 
74, 000 
74, 700 


5,520 
6,250 
5,390 
5,210 
5,700 
5,360 
5,700 
5,350 
5,550 
5,200 
5,250 
5,150 


17,433 
19,335 
23, 061 
23, 340 
18,114 
22, 080 
16, 683 
20, 766 
18, 852 
13, 720 
18, 026 
19,861 


1.70 
1.89 
2.25 
2.28 
1.77 
2.15 
1.63 
2.02 
1.84 
1.34 
1.76 
1.94 


21.11 
26.71 
30. 62 
30.81 
23.95 
29.15 
22.09 
27.51 
24.91 
18.25 
23.88 
23.65 


56.2 
56.6 
69.9 
71.4 
55.6 
60.6 
51.5 
54.7 
52.6 
45.6 
51.0 
60.4 


37.70 


1872... 


46.71 


1873 

1874 

1875 

1876 

1877 


43.85 
43.24 
43.07 
48.18 
42.92 


1878 


50.20 


1879 


47.24 


1880 


40.02 


1881 


46.93 


1884 - 


45. 15 






Period 


134,000 


5,150 


19,157 


1.87 


25.10 


57.0 


44.53 


1885. 


65, 550 

23, 200 
16, 400 
88, 600 
63, 700 
27,900 
10, 500 
18,000 
13, 100 
21,350 
78,200 
35,400 


17, 000 

10, 500 

7,600 

13,100 

10,250 

5,800 

6,000 

5,300 

6,000 

6,750 

12,400 

10,000 


34, 661 

14,711 

11,706 

26,250 

25,869 

10, 785 

7,909 

9,148 

8,105 

10, 084 

33, 067 

21,005 


3.38 

1.44 

1.14 

2.56 

2.52 

1. 06 

.77 

.89 

.79 

.98 

3.23 

2.05 


3.89 
1.50 
1.32 
2.86 
2.91 
1.28 

.89 
1.03 

.88 
1.13 
3.60 
2.36 


93.9 
51.4 
89.6 
102.4 
119.7 
40.0 
25.0 
12.8 
47.8 
24.0 
69.3 
72.0 


4.14 


February 

March 

April 

May 

June 

July 


2.92 
1.47 
2.79 
2.43 
3.20 
3.56 
8.06 




1.84 




4.72 




5.20 




3.29 








88, 600 


5,300 


17, 775 


1.73 


23.65 


54.3 


43.62 







Discharge and run-off of Housatonic River at Gaylordsville, 1901-1903 and 1906. 
[Drainage area, 1,020 square miles.] 



Date. 



1901. 
1902. 
1903. 



January... 
February.. 

March 

April 

May 

June 

July 

August 

September. 
October... 
November. 
December . 



1906. 



The year . 



Discharge (second-feet). 



Maxi- 
mum. 



14,300 
31,000 
25, 700 



3,170 
4,630 
10, 000 
8,930 
5,060 
2,370 
2,120 
1,310 
876 
2,220 
1,980 
1,440 



10,000 



Mini- 
mum. 



303 
525 
550 



Mean. 



2,216 
2,920 
3,006 



,130 
,460 
,090 
928 
421 
347 
296 
296 
550 



1,800 
1,630 
2,910 



296 



1,670 



Run-off. 



Per 
square 

mile 
(second- 
feet). 



Depth 
(inches). 



2.861 
2.946 



1.76 
1.60 
2.85 
4.69 
2.07 
1.60 
.965 
.802 
.543 
.844 
.973 



29.65 
38.62 
39.65 



2.03 

1.67 

3.29 

5.23 

2.39 

1.78 

1.11 

.92 

.61 

.97 

1.09 

1.08 



22.17 



Relation 

to rainfall 

(per 

cent). 



52.1 
62.9 
69.8 



84.2 
65.5 
81.0 
142.5 
42.6 
31.8 
17.2 
29.3 
17.0 
24.1 
80.1 
28.1 



47.9 



Rainfall 
(inches). 



56.94 
61. 43 
56.85 



2.41 
2.55 
4.06 
3.67 
5.61 
5.60 
6.47 
3.14 
3.58 
4.02 
1.36 
3.84 



46.31 



30 UNDERGROUND WATER RESOURCES OF CONNECTICUT. 

POPULATION AND INDUSTRIES. 

The physiographic division of Connecticut into highland and low- 
land areas has been a controlling factor in determining the settlement 
and character of life of the people of the State. The bulk of the 
population at the present time is grouped in three areas : 

First, the central lowland, containing the towns of New Haven, 
Hartford, Middletown, New Britain, Meriden, etc., in which 39 per 
cent of the entire population of the State is located. This region was 
first settled in 1637 and the population has increased gradually from 
that date. The favorable conditions of the lowland area are the fer- 
tile soil, which is readily tilled, and the ease of establishing lines of 
communication by wagon roads, canals, and railroads. 

Second, on the shores of Long Island Sound, where are located Nor- 
walk, Stamford, Bridgeport, New London, and other towns, which 
together have a population of 199,719, or 22 per cent of the total. 

Third, in the highland valleys, where Waterbury, Wins ted, Wil- 
limantic, and many smaller towns are located and where 26 per cent 
of the population reside. The original attractions of these places were 
the water power and ease of communication along valleys. Collins- 
ville is typical of many small villages that have been built up about a 
factory whose location was determined by excellent water power. 

The towns of the State outside of these three groups have attracted 
but 13 per cent of the population. The soil is thin but of fairly good 
quality. The roads have steep grades and are difficult to maintain. 
Railroad lines enter the highlands only along the wider valleys and 
are at an inconvenient distance from many of the towns. Parts of 
Union, Hartland, and North Stonington are 10 miles from any rail- 
road, and many farms in Killingworth, Salem, Goshen, Ashford, 
Canterbury, and Ledyard are nearly as inaccessible. The result is 
that the population of certain hill towns has actually decreased. 
During the decade from 1890 to 1900 ten towns out of twenty-six in 
Litchfield County showed a decrease in population and ten out of 
thirteen tfowns in Tolland County suffered a net loss in population of 
1,400. At the present time a new era seems to be dawning for rural 
Connecticut, partly as a result of improved methods of farming and 
of the introduction of the practice of scientific forestry, but more 
largely owing to the fact that the farms of the highlands are being 
purchased for summer homes and estates. For this purpose an 
abundant supply of good water is essential. In fact, the water re- 
sources of Connecticut form one of its chief commercial assets, and a 
knowledge of their character and occurrence has become a matter of 
great practical importance. 



CHAPTER II. 

GEOLOGY. 

OUTLINE OF GEOLOGIC HISTORY. 

Very little is known of the early geologic history of Connecticut. 
It is probable that some of the gneisses and schists date from a time 
before any living forms existed upon the earth, but no fossils older than 
the Triassic have been found in the State, and it is therefore impossi- 
ble to determine definitely to what age the pre-Triassic rocks belong. 
Their position in the time scale can, however, be determined approxi- 
mately by comparing them with similar rocks in regions where their 
relations are known. This study of adjoining regions, taken in con- 
nection with the detailed study of the structure of the rocks them- 
selves, indicates that the crystalline rocks of Connecticut have a 
long and complicated geologic history. 

Pre-Cambrian rocks are represented in the State by the Becket 
gneiss, but no data are at hand to determine definitely the origin or 
age of this formation. Its component parts have been so completely 
altered by changes that have taken place since their deposition that all 
evidence of value for determining their original character has been 
destroyed. The character of the rocks overlying the Becket gneiss 
indicates that a sea extended over a large part of Connecticut during 
Cambro-Ordovician time and that the Stockbridge limestone and 
associated quartzites were deposited in that ancient water body. 
Such an accumulation of material implies the wearing down of land 
masses and suggests that lands of considerable elevation must have 
existed to the east of the present shore line. 

The long interval between the close of the Ordovician and the begin- 
ning of the Mesozoic time has left no legible records of deposits that 
can be assigned to any definite geologic period. The great thick- 
ness of Devonian sediments to the west suggests a New England 
mountain range of considerable height which furnished material for 
the sedimentary strata. 

One series of events, however, is abundantly attested, namely, 
that igneous intrusions occurred frequently in the interval between 
the Ordovician and the Triassic periods, resulting in the formation of 
numerous veins and dikes of quartz and granitic and basic rocks. 
The nature of these intrusive masses indicates that they have been 

31 



32 UNDERGROUND WATER RESOURCES OE CONNECTICUT. 

brought to the surface by the removal of thousands of feet of sedi- 
ments. The particular date of any of these igneous intrusions is 
unknown, but their effect is well shown, and it is not at all unlikely 
that part of the molten rock reached the surface and was represented 
by volcanic activity, ail traces of which have disappeared. 

The geologic records show also that at different times between the 
Ordovician and the Triassic there were important movements in the 
earth's crust which resulted in the metamorphism of all the existing 
rocks in the State. Just when these profound changes took place is 
unknown, but the rocks are believed to have been involved in the 
great earth movements which produced mountains at the close of the 
Archean, Ordovician, and Carboniferous periods. 

That many changes took place in Connecticut during the time from 
the Ordovician to the close of the Carboniferous is shown beyond 
doubt by an examination of the highland areas. 

These rocks are chiefly schists and gneisses, and accordingly have structures indi- 
cating that they have been profoundly changed from their original sedimentary or 
igneous character. The original component minerals have been rearranged, stretched, 
and drawn out in lines; new minerals have been produced ; parts have been fused and 
recrystallized. Instead of horizontal layers or uniform igneous masses, we find 
twisted and broken rock with layers, bands, and ribbon structures in every conceiv- 
able position. This tangle of structure is further complicated by the presence of dikes, 
seams, and veins which have made their way into the rock at different stages of its 
history. In looking at this confused mass of rock which forms the Connecticut crystal- 
lines, it seems apparent that it has taken part in manifold changes which went on in 
the earth's crust for ages. This very complexity of structure is an important aid in 
determining the relative age of the rocks, for it is evident that in general the oldest 
rocks must have been affected by the greatest number of disturbances, and accord- 
ingly the rocks of one age may exhibit structures not found in those of succeeding 
ages. In the absence of other criteria the geologist is forced to fall back upon this. 
These rocks are like a parchment on which writing after writing has been placed at dif- 
erent times by different hands, without at any time completely erasing the previous 
inscriptions. Little wonder that we have difficulty in deciphering the original writing. 

Such composition and structure as is described above can be produced only at very 
great depths in the earth (probably below 20,000 feet) where rocks are so deeply buried 
that, whatever the lateral stress, they will not adjust themselves by breaking, but by 
plastic deformation. It is therefore certain that, whatever the age of the crystallines, 
mountain ranges perhaps rivaling the Alps in height and ruggedness once occupied 
central Connecticut; and when we examine the rocks of Satans Kingdom, or the Quin- 
nebaug Valley, or the Connecticut gorge below Middletown, or indeed any part of the 
area of crystalline rocks, we are studying the roots of lofty land masses composed of 
strata deposited during part or all of the Paleozoic era.° 

The land at the close of the Carboniferous was probably marked by 
rugged topography — the hills and valleys making prominent scenic 
features. During Triassic time these elevations were removed and 
the material from the crumbling hills was built into the sandstones 
of central Connecticut. 

a Rice, W. N., and Gregory, H. E., Manual of Connecticut geology, 1906, pp. 80, 81. 



GEOLOGY. 33 

The Triassic rocks are very much younger than any of the crys- 
talline rocks exposed within the State; in fact, it is possible that no 
rocks were formed for a long period before the deposition of the 
lowest sandstone stratum. Where the ancient crystalline rocks and 
the Triassic rocks come into contact there is a marked unconformity, 
the sandstones lying upon the upturned edges of schists and gneisses 
of ancient time. The Triassic sandstone was deposited in water 
which was fresh or perhaps brackish, and a great deal of it was 
deposited in water which must have been shallow. The presence of 
animal life is indicated by the fossils found in the sandstones and 
shales. Skeletons of dinosaurs have been recovered and thousands 
of tracks of these strange animals have been found in the quarries of 
the Connecticut Valley. The shales at Saltonstall and Durham and 
elsewhere contain abundant remains of fish. 

During the long time throughout which the Triassic sediments 
were being deposited volcanic eruptions formed widespread lava 
flows extending from New Haven to the northern line of the State. 
Outbursts of lava occurred at three different times and the fields of 
basalt which represent these flows are separated by considerable 
thicknesses of shale and sandstone, indicating periods of volcanic 
activity followed by long periods of quiet. 

The sandstones and lavas of Connecticut were laid down in an 
approximately horizontal position, but at a date later than the 
Triassic the flat-lying beds were broken by a series of faults extending 
diagonally across the central lowlands. Displacement along these 
fault lines formed a series of giant blocks, composed of sandstone and 
trap, that were elevated on the west side and depressed on the east. 
The topographic result was a series of ridges with steep westward 
escarpment and gently sloping eastward face. 

During Cretaceous time the entire region seems to have been worn 
down to a plain practically at sea level and sloping gently from north- 
west to southeast. Hills stood above the plain, but not to such an 
extent as to give the country a rugged topography. The southern 
part of the State at this time was probably covered with sediments 
deposited in a Cretaceous sea which extended to the latitude of 
Hartford. The result of this long period of erosion was to reduce the 
inequalities produced by the uplifting of the blocks of sandstone and 
lava and to lessen the contrast between highland and lowland areas. 

Near the beginning of the Tertiary period the area now forming 
the State was uplifted and the streams which had been wandering 
across the Cretaceous plain were revived and began once more to cut 
their channels and to carry sediment to the sea. The result was to 
bring into relief all the harder and more resistant rock masses by 
removing the softer material. For example, in central Connecticut 
the areas of resistant trap stand above the sandstone plain as ridges 
463— irr 232—09 3 



34 UNDERGROUND WATER RESOURCES OF CONNECTICUT. 

whose length and shape had been previously determined by the 
direction of the fault lines. In the same way the softer Cretaceous 
strata along the coast seem to have been entirely removed and the 
less resistant limestone of the Housatonic Valley reduced to a narrow 
lowland. As a result of this long period of stream erosion during 
Tertiary time, the topography of the State acquired the larger general 
features of the present time. 

During the Pleistocene ("Glacial") epoch the topography of 
Connecticut was again remodeled. The continental ice sheet which 
covered the northern part of America extended entirely across New 
England. Its thickness was great, the power urging it on was irre- 
sistible, and accordingly the landscape was molded in a characteristic 
manner. The loosened soil covering was removed from the rocks and 
the rocks themselves were reduced in height. They were grooved 
and scratched and polished by the pebbles embedded in the ice. A 
great quantity of material was removed permanently from the area 
and carried to Long Island. Although the larger features of the 
topography left by Tertiary erosion were little changed when the 
glacier disappeared, the details were greatly modified. Instead of the 
soil formed by the decomposition of the rocks, the glacier left two 
types of surface covering — glacial till, an unassorted and unstratified 
mass of rocks, bowlders, clays, and sands, differing widely in size and 
in composition, and stratified drift composed of layers of sands 
and gravel. The till came directly from the material carried by the 
glacier. The stratified drift was deposited by the waters from the 
melting ice mass. The distribution of this glacial material over the 
entire region modified the shape of hills, filled valleys, blocked 
drainage courses, rearranged stream channels, and left many depres- 
sions filled with bodies of water, so that although the main streams, 
like the Connecticut and the Housatonic, are now flowing in courses 
inherited from Tertiary time, yet the smaller streams owe their 
present arrangement very much to the changes produced by glacia- 
tion. Waterfalls, lakes, ponds, and swamps are also records of the 
Pleistocene ice invasion. 

DESCRIPTIVE GEOLOGY. 

INTRODUCTION. 

The occurrence of ground water and the methods of its recovery 
are determined by the structure of the rocks, and therefore a knowl- 
edge of the character of the geologic formations of a region is essen- 
tial to the well driller and to the well owner if. he desires to attain 
satisfactory results at minimum expense. In Connecticut a well in 
mica schist may need to be of different construction from one in 
sandstone and will yield water differing in amount and in quality. 
Wells in till are usually shallow and of large diameter; those in 



GEOLOGY. 35 

stratified drift are particularly liable to contamination; those in 
sandstone and shale rarely yield water that is suitable for boilers. 
Thus in many ways the rock formations represented in the State 
determine the nature and value of the water supply. 

In Connecticut three widely different rock groups must be taken 
into account by the well driller — the crystalline rocks forming the 
western and eastern highlands; the sandstones of the central 
lowland; and the deposits of sands, gravels, and clays which overlie 
all the rocks of the State. The sandstones, shales, and conglom- 
erates are of Triassic age, as is shown by the numerous fossils con- 
tained in them. The gravels and other surficial deposits are of 
Pleistocene age. The crystalline rocks are of much greater antiquity, 
but owing to the absence of any definite marks of identification 
they will be referred to simply as pre-Triassic. 

CRYSTALLINE ROCKS. 
DISTRIBUTION AND CHARACTER. 

With the exception of the area underlain by Triassic strata, the 
entire State of Connecticut is occupied by crystalline rocks of very 
great age. They are of two types, igneous and metamorphic, both 
widely different from the sediments of the valley lowlands. 

Igneous rocks are those which have been molten and have solidi- 
fied from cooling. They are accordingly composed of crystals, 
closely fitted and interlocking, instead of being made up of grains or 
fragments of material, as are sandstones. The many different 
textures shown by these igneous rocks were determined by their 
rate of cooling, and in accordance with this principle fine-grained 
granites and granite porphyry have been formed. Unchanged 
igneous rocks are rare in Connecticut outside of the traps of the 
Triassic region. They occur as veins, dikes, and small bosses, 
mostly of granite and related rocks. A few diabase dikes are dis- 
tributed along the borders of the lowlands. The masses of unaltered 
igneous rock within the ancient crystalline areas are so small that 
it has not been found desirable to indicate them on the geologic 
map of the State. a 

Metamorphic rock constitutes practically all of the crystalline 
areas in Connecticut. Rocks of this type have been profoundly 
changed from their original condition either as igneous or sedimen- 
tary. The change in some of these rocks is merely a hardening, as 
when shales are baked by the intrusion of a trap dike. But the 
metamorphic rocks of the State as a whole show much more complete 
alteration. Their mineralogical composition has been changed, 
their structure has been destroyed, and fossils which they may 

a Bull. Connecticut Geol. and Nat. Hist. Survey No. 7, 1907. 



36 UNDERGROUND WATER RESOURCES OF CONNECTICUT. 

have formerly contained have been obliterated. The changes have 
been so great that the rocks bear little resemblance to their former 
appearance, and with some of them it is impossible to determine 
whether the original material was igneous or sedimentary. 

The metamorphic rock masses existing within the State are 
crystallized limestone (marble), quartzite, phyllite, schist, and 
gneiss. Marble is a metamorphosed limestone, in which the grains 
of the original rock have been converted into crystals. Quartzite is 
a sandstone which has been made firm and compact by filling in the 
spaces between the sand grains with quartz. Phyllite is usually an 
advanced stage in the development of slate, which in turn is made of 
mud shales and related rocks. Schists and gneisses are so widespread 
within the State that they might be said to constitute the bed rock 
of the region. Twenty-three varieties of gneiss and eight varieties 
of schist are shown on the Connecticut geologic map. Schist is a 
term used to indicate the structure of the rock, not its composition, 
and represents an extreme stage of metamorphism in a rock which 
may have been originally igneous, sedimentary, or metamorphic. 
In schists so far has metamorphism proceeded that new minerals 
have been made, particularly mica, and a complete rearrangement 
of the mineral particles has taken place. 

The value of the crystalline rocks as water carriers is determined 
by the facts that they are very dense, nonpermeable rocks, that 
structures of slatiness and schistosity are developed in them, that 
they are traversed by numerous joints in many directions, and that 
they are cut by large or small faults. 

Schists are characterized by cleavage planes which enable the 
separation of the rock into irregular layers of small thickness. The 
structure which admits of the splitting of the rock in this manner is 
called schistosity and owes its origin to the parallel arrangement of 
micas and other flat minerals whereby separation takes place in one 
direction much more readily than in others. Schists always contain 
an abundance of mica, but they contain also other minerals in large 
amounts. Feldspar is invariably present, and a typical mica schist 
consists essentially of feldspar, mica, and quartz. The names horn- 
blende schist, quartz schist, kyanite schist, etc., used in the following 
pages, indicate the prominence of certain minerals. Most of the 
Connecticut schists are believed to be the metamorphic equivalents 
of sedimentary rocks, the Hoosac ("Hartland") schist, for example, 
having previously been a series of sandstones, shales, and limestones, 
much like the present sediments of the Triassic belt. 

Gneiss, like schist, is a term which refers only to the structure of a 
rock and implies the existence of a series of roughly parallel break- 
ing planes along which the rock may be separated into slabs of various 
sizes. The development of schistosity is alike in gneisses and schists, 



GEOLOC.Y. 37 

but gneiss is more massive and is commonly the present equivalent 
of former igneous rocks. The production of gneiss from granite has 
taken place within the Connecticut area on a large scale. Granite 
masses have been stretched and squeezed so that instead of being of 
uniform texture and massive structure they are drawn out into 
sheets and definite layers. Practically all of the granite quarried 
within the State is granite gneiss, the gneissoid structure of which 
is an important factor in successful quarrying. 

When schists or gneisses are exposed to the atmosphere the planes 
of schistosity often become definite cracks and open fissures into 
which water may descend and collect in amounts sufficient to supply 
wells or springs. It is this capacity to carry water which makes a 
detailed study of the structure of rocks a matter of practical impor- 
tance. 

JOINTS. 

Rocks do not as a rule present an unbroken surface over any con- 
siderable area, but are traversed by cracks, which vary in size from 
those that are scarcely visible to those that are several inches in 
width. These cracks or "seams," as they are called by drillers and 
quarrymen, are technically joints. They are the results of mechan- 
ical action in rocks, which breaks them into more or less regular 
polygonal blocks separated by open spaces, and they are therefore 
of great importance when water-storage capacity is considered. 

The most common type of j oints includes those which are approxi- 
mately vertical and cross each other at various angles, giving the 
rock surface the appearance of a rough screen or network. The prev- 
alence of vertical jointing is shown by the fact that the inclination 
of about seventy-five measured joint planes in the Connecticut 
crystalline rocks was found to average 74°, forty of the joints being 
practically 90° from the horizontal. Another set of joints in the 
crystalline rocks runs more or less parallel to the surface of the rock. 
Some of these joints correspond to gneissoid and schistose structures, 
but many others represent entirely different planes of cleavage. In 
the gneissoid granites, as at Maromas and Glastonbury, these hori- 
zontal joints occur, but they vary considerably in their extent, num- 
ber, spacing, and direction, as well as in width of opening, a variation 
which seems to depend primarily on the character of the rocks which 
they traverse. In the gneisses, particularly in gneissoid granites 
and granodiorites, the horizontal joints are very well developed and 
constitute the so-called " bedding" of the quarrymen. In the schists 
and the less massive gneisses horizontal jointing is poorly developed 
and in places even lacking. The character and number of vertical 
joints also depend on the nature of the rock. Certain rocks seem to 
be thoroughly shattered and broken by vertical joints into small 



38 UNDERGROUND WATER RESOURCES OF CONNECTICUT. 

wedges and blocks a fraction of an inch in diameter. Other rocks, 
like pegmatites, may extend for 25 to 50 feet without being marked by 
a prominent line of breaking. A good illustration of the difference 
of the jointing in two types of rock is seen in the Milford chlorite 
schist, where much fractured schistose and slaty varieties occur 
immediately in contact with fairly compact masses of altered diabase. 

FAULTS. 

Fractures along which more or less vertical movement has taken 
place are called faults and have been frequently observed in outcrops 
of crystalline rock. Many of the fractures extend to considerable 
depths and may appear on the surface as single lines or as zones of 
closely packed joints or of shattered rock. Much ground water may 
be stored in zones of faulted rock, and the open spaces afforded for 
the movement of water make fault lines of great value as channels for 
spring waters and supplies for wells. 

TRIASSIC SANDSTONE AND TRAP. 
DISTRIBUTION. 

The Triassic rocks of the State occur in two areas — one extending 
from the Massachusetts line to Long Island Sound, with a breadth 
of about 20 miles at Thompsonville and narrowing at New Haven 
to the width of the harbor, the other underlying the- towns of South- 
bury and Woodbury. Both of these areas are links in a broken 
chain of similar Triassic deposits which extends from North Carolina 
to Minas Basin, on the Bay of Fundy, a distance of 1,200 miles, and 
which covers altogether 10,000 square miles. 

STRATIGRAPHY. 

The relation between the Triassic strata and the ancient crystalline 
rocks is seen at Roaring Brook, in Southington, where sandstone lies 
unconformably upon the upturned edges of the Hoosac (" Hartland " ) 
schist. A general study of the Triassic areas of the Atlantic coast 
leads to the belief that the Connecticut areas are parts of a much 
larger expanse of Triassic rocks and that they owe their present 
existence to the fact that they have been dropped down as a result 
of faulting, and thus protected from the erosion which removed the 
adjoining areas exposed at higher levels. 

The rock types existing in the Triassic area are two — the lavas 
(basalts) and intrusive sheets and dikes (diabase), rocks which are 
called popularly a trap;' ; and the sandstones, which range in texture 
from fine shales to extremely coarse conglomerates. The strati- 
graphic series in the Triassic of Connecticut consists of three lava 



GEOLOGY. 39 

flows with sedimentary strata below, between, and above them. 
Their relations are shown by the following table: 

Stratigraphic succession in Triassic rocks of Connecticut. 

Pre-Triassic metamorphic rocks. Feet. 

"Lower" sandstones 5, 000-6, 500 

' ' Anterior " a (lower) trap 250 

"Anterior " shales and shaly sandstones 300-1, 000 

"Main " (middle) trap 400-500 

"Posterior" shales 1, 200 

"Posterior" (upper) trap 100-150 

' ' Upper " sandstones •. . 3, 500 

The " Lower" sandstone varies in texture from a fine-grained 
rock in the vicinity of Avon and Granby to a coarse conglomerate 
in which some of the pebbles exceed 2 feet in diameter. Where 
typically exposed in the quarries at Fair Haven the rock consists 
of fragments from the bordering crystalline rocks, including abundant 
crystals of feldspar, pebbles of quartz, fragments of porphyries, 
gneisses, and schists. Great variation is shown in the composition 
and structure of the beds, and abrupt changes in the character of the 
rock are observed at many places. In general the stratification is 
uneven and irregular, and the coarser and finer materials have 
rather the character of lenses than of uniform beds of wide extent. 

The "Anterior" and "Posterior" sandstones contain a much 
larger proportion of shales than the "Lower" sandstones; in fact, 
shales and shaly sandstones are characteristic of these formations. 
In certain places, as east of Southington, an impure limestone occurs, 
and in a number of localities there is a slightly bituminous black 
shale. The stratigraphic position of the black shale is 50 to 100 
feet above the "Anterior" trap sheet and at different levels between 
the "Main" and "Posterior" traps. The presence of these beds of 
shale has an important bearing on the problem of water supply. 
(See p. 109.) Fossil fish have been discovered in them at Saltonstall 
Lake, Rocky Hill, Durham, and other localities. 

The "Upper" sandstones, consisting of sandstone and shale, with 
conglomerate locally developed, constitute the Triassic strata east 
of the central trap ridge. It is in these sandstones that the quarries 
at Portland and Long Meadow are located. In certain localities the 
"Upper" sandstone has characteristic features, but as a rule it 
is not a distinct formation. As stated by Davis, 6 "the Anterior, 
Posterior, and Upper sandstones and shales are seldom distin- 
ct Owing to the monoclinal faulting which has broken the Triassic strata into eastward-tilting blocks, 
the traveler going from west to east across the Connecticut lowland comes first to the lowest and 
oldest lava flow, next to the middle, and last to the uppermost. Hence the terms "Anterior," 
"Main," "Posterior," first used by Percival. 
b Eighteenth Ann. Rept. U. S. Geol. Survey, pt. 2, 1898, p. 139. 



40 UNDERGROUND WATER RESOURCES OF CONNECTICUT. 

guishable." It is also true that these three formations are practi- 
cally indistinguishable from the " Lower" sandstones. 

The three lava flows — " Anterior/' "Main," and "Posterior" — 
are identical in chemical and mineralogical composition and are 
manifestly of closely similar origin. They are flows of basalt from 
unknown sources. The "Anterior" trap is broken into a series of 
small hills and short ridges at Saltonstall, Totoket Mountain, Lamen- 
tation Mountain, and other places, and disappears in the vicinity 
of "Newgate Prison," in East Granby. This trap sheet is com- 
paratively dense, but is vesicular on the upper surface, and at Lamen- 
tation Mountain it contains an "ash bed" of fine lapilli, 30 feet thick. 
The "Main" trap sheet is made up of two or more flows with a 
combined thickness of 400 to 500 feet and constitutes the most 
prominent topographic feature of central Connecticut, forming the 
conspicuous ridges beginning at Saltonstall and extending through 
Meriden and Farmington and into Massachusetts, where they include 
Mount Tom and Mount Holyoke. The "Posterior" trap follows the 
"Main" trap sheet in general alignment and has similar character- 
istics, but at only a few places does it become an important topo- 
graphic feature. An excellant view of the "Posterior" trap and 
the underlying sandstones may be obtained at the city quarry, 
Hartford, immediately adjoining the buildings of Trinity College. 

In addition to the three lava flows there is a series of intrusive 
trap sheets and dikes composed of diabase. East and West rocks 
at New Haven, Gaylord Mountain, the ridges east of Canton, and 
the Barndoor Hills are examples. 

JOINTS. 

Both the sandstones and the traps of Connecticut are traversed 
by many prominent joints, which form reservoirs for ground water. 
Where exposed in quarries the sandstone is seen to be cut by numerous 
joints and open fissures, so that even in the most favorable localities 
it is impossible \o quarry slabs of stone of very large size. The 
principal joints are nearly vertical and intersect each other at fairly 
wide angles, so that the finer-grained sandstone and the shale break 
in more or less uniform blocks. In the Hartford quarry the shale is 
traversed by two prominent sets of cracks, which enable the workmen 
to remove diamond-shaped blocks about a foot in diameter. The 
conglomerate, especially where it contains large quantities of quartz, 
exhibits much less uniformity in jointing than the finer-grained rocks. 
The blocks into which it breaks are wedges and rude polyhedrons of 
such a variety of form as to make it impossible to predict the location 
of definite division planes. Many of the joints in the sandstone are 
weathered to great depth and furnish ready passage for water. (See 
pp. 73-74, 111-113.) 



GEOLOGY. 41 

The trap rocks are of such uniform texture and of such fine grain 
that the jointing is exhibited on a very elaborate scale. Usually the 
joints are barely visible, but in a few places they are widely open and 
some of them have been filled with secondary material. The in- 
trusive traps, and some of the lava flows as well, show a decided joint- 
ing at right angles to the plane of cooling, which gives a rudely 
columnar structure to the rock. In the New Haven region the 
columns are beautifully developed at Rabbit Rock, and some of the 
dikes in the Fair Haven tunnel show a regular and uniform system of 
joint cracks. 

Perhaps the most convincing evidence of the abundance and in- 
fluence of joints in trap is furnished by exposed cliffs below which 
is a talus slope of broken trap formed by joint blocks derived from 
the ledge above. Practically every high trap ridge in the State is 
flanked by such jumbled masses of fragments, the size and shape of 
which is determined by the direction and spacing of the cracks in 
the ledge. On the exposed edges of cliffs the joints furnish ample 
facilities for the free circulation and storage of water. In fact, where 
the bed rock is trap these cracks contain almost the only, water supply 
within reach of wells. 

FAULTS. 

The sandstones and lavas of the Triassic area were laid down in a 
horizontal position. They no longer retain that attitude, however, 
but dip to the east at an average angle of 15° to 20°. In a few places 
the strata lie practically flat, and locally the dips are as high as 40°. 
These dips are due to the fact that the region is crossed by a series of 
fault lines which have cut the strata into blocks that are tilted to the 
east. Faults are joints or cracks in rock along which movement has 
taken place and which, accordingly, disturb the continuity of the 
rock much more profoundly than simple joints. In the lowland area 
twenty-five faults have been traced which extend for 5 miles or more, 
and one fault extending between Hanging Hills and Lamentation 
Mountain extends northeast and southwest for 40 miles. Innumer- 
able smaller faults exist and may be observed in practically every 
outcrop of trap or sandstone. In places they occur so abundantly 
and are so closely placed that the rock appears to be shattered into 
small fragments. The amount of slipping which has occurred along 
these fault planes varies from a few inches, observed in quarries and 
railroad cuts, to several thousand feet in the great diagonal faults 
which have brought the "Lower" sandstones of Lamentation Moun- 
tain up to the level of the "Posterior" trap. The uplift in most of 
these faults is on the east side of the fault line, which accounts for 
the eastward dip of the strata and for the westward-facing cliffs. If 
the faults extended in the direction of the strike of the strata a series 



42 UNDERGROUND WATER RESOURCES OF CONNECTICUT. 

of parallel ridges would be exposed, marked by prominent cliffs of 
erosion on the west side. But the faults have traversed the forma- 
tions obliquely, most of them from northeast to southwest, with the 
result that the erosion has produced a series of blocks which are not 
in alignment but are offset to one side or the other and separated by 
passes and gaps and notches. 

The small Triassic area in the Pomperaug Valley presents features 
practically identical with those in the central lowland, and therefore 
requires no separate description.® 

PLEISTOCENE DRIFT. 
DISTRIBUTION AND GENERAL RELATIONS. 

The glacial deposits of Connecticut form a mantle covering the 
bed rock practically everywhere. It is doubtful if bare rock is 
exposed over one-tenth of 1 per cent of the surface. The drift in 
thickness varies from a mere film to masses 300 feet in depth which 
have obliterated, ancient stream courses. It is not quite so thick 
near the Sound and on the highlands as in the major valleys, and the 
rock ledges are confined for the most part to the summits of ridges 
and projecting cliffs now partly covered with talus. The disinte- 
grated rock material formed throughout earlier geologic ages was 
removed by the glaciers, so that in general the rock surface where 
exposed is firm. Immediately overlying the solid rock, but with a 
marked unconformity between, is the glacial drift. The surface 
material as a rule has not originated from the rock on which it rests, 
and it may be entirely different in composition as well as in texture. 
Drift fragments of gneiss may be in immediate contact with shale, 
and bowlders of sandstone and trap may form the soil above ledges 
of mica schist. The fact that the bed rock is everywhere covered 
with glacial drift is one of the most important factors in the under- 
ground water problem of Connecticut, for the drift acts as a reser- 
voir to feed water into the joints and cracks of the bed rock under- 
neath. (See p. 142.) 

CHARACTER OF MATERIAL. 

Two types of glacial material are exhibited in the State — till and 
stratified drift. The till was made directly by the glacier and 
consists of deposits which are characteristic and quite unlike those 
made by water or wind. Glacial ice does not sort material, and the 
result is that till is composed of bowlders, sands, clay, and pebbles 
of all sizes, confusedly intermingled; and the same outcrop may 
show a heterogeneous lot of bowlders mixed with finely ground 

o For a complete discussion of the faults of the Woodbury-Southbury region see Hobbs, W. H., Twenty- 
first Ann. Rept. U. S. Geol. Survey, pt. 3, 1901, pp. 7-162. 



GEOLOGY. 43 

clay and sand. The bowlders may be securely bedded in rock flour 
in such a manner as to form "hardpan," which is scarcely less friable 
than artificial concrete and which furnishes little access to water; or 
the whole mass may be composed of bowlders and sand with large 
spaces between the fragments. Ordinarily the till is spread more 
or less uniformly over a region with a thickness depending on the 
character of the underlying topography, but here and there it is 
built into mounds (drumlins) which have been overridden by the 
ice, much as sand bars are formed in rivers. 

Most of the rock fragments composing the till have not been 
rounded by water, and although much worn they are subangular and 
in many places polished and grooved and striated. The innumerable 
bowlders strewn over the surface of the State, built into fences, or 
used for foundations are parts of the till left by the retreating glacier. 

Stratified drift consists of rounded fragments of sand and gravel 
deposited by water from the melting ice and differs little in appear- 
ance from deposits made by rivers or by the ocean. It differs from 
till in being stratified — that is, it is arranged in layers of fine and 
coarse material; and although the original fragments are the result 
of the grinding action of the ice sheet, the present position and struc- 
ture of the drift are due to glacial waters. Stratified drift usually 
forms sand plains, and is confined chiefly to valleys and lower levels. 
Certain long winding ridges of stratified drift, indicating the channels 
of preglacial streams, are called eskers, and in some places the 
stratified drift takes the form of knobs, short ridges, and kettle 
holes, which are due to water action under conditions of confinement. 



^CHAPTER III. 

OCCURRENCE AND RECOVERY OF GROUND WATER. 
CIRCULATION OF GROUND WATER. 

THE WATER TABLE. 

The term "ground water" is used in referring to water supplies 
obtained from wells or springs, in contrast with those derived from 
streams and lakes. The ground water represents that part of the 
rain or snow which penetrates into the soil, while the remainder of 
the precipitation is delivered directly to surface streams, evaporated, 
or absorbed by vegetation. 

The clearest conception of the circulation of ground waters may 
be obtained by considering the material in which they occur to be of 
a uniform character. Every one is familiar with the fact that a hole 
dug in the sandy beach of the sea or of a lake will fill with water to 
the level of the sea or lake water, and in a sea-beach hole the level of 
the water will lower as the tide goes out. As holes or wells are dug 
at greater distances from the shore and at higher elevations the level 
of the water in the wells is found to rise above that of the surface of 
the lake, river, swamp, or other body of water with which the com- 
parison is made. The height to which the water will rise at any 
point in the ground is known as the height of the water table at that 
point. The water table therefore represents the upper limit of a zone 
saturated with water, above which the ground is relatively free from 
water except immediately after rainfall. It is the surface of the sea 
of ground water, and it is also called the " ground-water level." 

The water table has a surface rising and falling with the land sur- 
face, but with smaller differences of elevation. The water has the 
highest elevation on the hills and the lowest in the depressions, but 
stands farthest from the surface of the ground on the hills and rises 
nearest to the surface in the depressions ; where these are deep enough 
it reaches the surface to form swamps, lakes, and streams. Where 
the ground is perfectly level and uniform in character the level of the 
water table is uniform, but where changes occur in the surface elevation 
the water flows from the higher to the lower points, and there is thus 
a constant movement of the ground water from the hills toward the 
valleys. With surface waters this movement is unrestrained and the 
water immediately runs off the hills; but the movement of ground 
waters is very slow, owing to the frictional resistance to the passage 
44 



OCCURRENCE AND RECOVERY OF GROUND WATER. 45 

of the water through the small openings of the soil and rock. This 
slowness of movement makes possible the existence of shallow dug wells 
on hills, and it is also the cause of the constancy of flow of streams 
and springs throughout the year. If the ground water moved as freely 
as the surface water the streams would have exceedingly large flows 
immediately after heavy precipitation and would be dry in the inter- 
vals between rains. 

MOVEMENT OF GROUND WATER. 

The movement of ground water is due to the force of gravity, and 
accordingly tends to take a vertical direction. After a rainfall the 
water absorbed by the ground gradually percolates downward 
through the soil until it reaches the water table, where the motion of 
the sea of ground water instead of being vertical is mainly in the 
same direction as the slope of the surface. This slowly moving body 
of ground water finally comes to the surface. Some of it emerges as 
springs or as a succession of small seepages along the banks of streams, 
but a considerable proportion of it probably enters streams and lakes 




Figure 5. — Diagrammatic section illustrating seepage and growth of streams. Lines with arrows are 

lines of flows. 

below the water level. The general directions of flow of ground 
water and the manner in which streams are supplied are indicated in 
figure 5. 

Although the circulation of ground water is in a general way as 
stated above, it happens that natural conditions rarely afford a uni- 
form material in which the level of the water table may be predicted 
at any point. The ground is nearly everywhere made up of mate- 
rials varying in character and offering different degrees of resistance 
to the circulation of water. In Connecticut the ideal conditions are 
most nearly realized in some of the flat sandy plains of the Connecti- 
cut Valley. 

POROSITY. 

The circulation of water in any material is directly dependent on 
the amount and character of the openings in that material, and these 
openings may be in the form of small pores, of long flat joints or 
other fractures, or of irregular rounded and. tubular openings varying 
in size. 



46 



UNDERGROUND WATER RESOURCES OF CONNECTICUT. 



All rocks are composed of masses of separate particles or grains 
which do not touch each other at all points, small irregular openings 
occurring between the grains. This pore space, called " porosity," 
varies greatly in different materials and is largest in rocks that are 
composed of rounded grains laid down under water and least in rocks 
that have solidified from a molten condition. The porosity of a rock 
is expressed as a percentage of the entire volume. If 100 cubic feet 
of sandstone can absorb 20 cubic feet of water the rock is said to have 
a porosity of 20 per cent. 

The following table gives the percentage of pore space and the 
amount of water absorbed per cubic foot by various sorts of rocks: 

Porosity of different rocks. 



Rock. 


Percent- 
age of 
pore 
space. 


Water 
absorbed 

per 
cubic foot 
(quarts). 


Sandstone 


4.81 
28.28 
.14 
13.36 
.184 
3.578 
.969 


2-6 


Do 




Limestone 


i-li 


Do 




1 5 


Marble 






Do 






Granite 




rhri 


Do 




Slate 




.099 
.304 




Do 






Chalk 





4-8 


Sand 


8 10 


Clay 


10-12 


1 





These figures represent the ordinary limits of the porosity of the 
rocks and are derived from different sources. 



PERMEABILITY. 

The permeability of a rock is a measure of its ability to transmit 
water and is the most important factor in determining its value as a 
source of water supply. Permeability is dependent on the amount 
and character of porosity and on the existence of other openings, 
such as joints and other fractures and the small openings formed by 
escaping gas in certain lava flows. 

In order that water may readily pass through a rock it is necessary 
that the openings be of appreciable size and have good connection 
with one another. In openings of small size the flow of water is 
strongly opposed by friction and by the attraction between the 
sides of the openings and the water, which in very small openings 
is sufficient to cause all the water to adhere to the sides as if glued. 
The effect of small size of openings is well shown by clays such as the 
brick clays of the Connecticut Valley, which may absorb water equal 
to 40 per cent of their weight, indicating a high porosity, but which 
allow water to pass through only with extreme slowness. In clays 



OCCURRENCE AND RECOVERY 0¥ GROUND WATER. 



47 



the constituent particles are so small and of such angular shape that 
the individual pore spaces are exceedingly minute, though in the 
aggregate of considerable volume. In sandstones the openings are 
so large as to allow relatively rapid flow. In general the size of the 
pores and consequently the permeability decrease with decrease in 
size of grain. Slichter a has made the following calculations, based 
on experimental work, of the velocity and amounts of ground water 
passing through materials of different grades. 

Velocity of ground water in materials of different grades, pressure gradient 10 feet to the mile. 



Material. 


Diameter 
(milli- 
meters). 


Distance traveled per 
year. 




Miles. 


Feet. 




0.2 
.4 
.8 

2.0 


0.010 
.041 
.16 

1.02 


52.8 




216.0 




845.0 




5,386.0 







Flow of ground water in materials of different grades through a bed of vertical cross section 

200 by 1,000 feet, sloping 10 feet to the mile. 

Cubic feet 
per minute. 

Fine sand 5. 5 

Medium sand 22 

Coarse sand 87 

Fine gravel 546 

These determinations assume a uniform size of grain, a uniform 
porosity of 32 per cent, and a temperature of 50° F. 

The law of flow through homogeneous porous materials is that the 
quantity of flow varies as the square of the size of the soil grain, 
other factors being constant. This law is based on the assumption 
that the grains are unconsolidated, but in all sandstones there is 
more or less cementing material which binds the grains together and 
necessarily decreases the amount of pore space. The more highly 
cemented the rock the less the porosity, although the cementation 
itself is an indication of former free circulation, as it is due to the 
deposition of mineral matter from water. Other factors influencing 
the amount of flow are variations in porosity and in temperature. 6 
The flow at 70° F. is about double that at 32° F., owing to the fact 
that the viscosity of water decreases rapidly with rise in temperature. 

The influence of joints and other fractures is of increasing impor- 
tance as the porosity and size of the pore openings decrease, and in 
thoroughly crystalline rocks the only water circulation of conse- 
quence is through fractures. The rapidity of flow through joints is 

a Slichter, C S., Motions of underground waters: Water-Supply Paper TT, S. Geol. Survey No. 67, 1902, 
pp. 29, 30. 

b Slichter, C. S., op. cit., p. 25. 



48 



UNDERGROUND WATER RESOURCES OF CONNECTICUT. 



not known, but it is undoubtedly much greater than through the 
pores. Owing to the differences in the permeability of rocks water 
has decidedly different rates and amounts of flow in adjacent mate- 
rials. The main flow of water is confined to the most permeable 
formation, other conditions being equal. 

Most underground waters yielding supplies of economic importance 
are under more or less modified artesian conditions; that is, they 
follow definite inclined channels or zones, inclosed by material more 
impermeable to water than that carrying the water, and rise to some 
extent above the level where they are struck. 

ARTESIAN CONDITIONS. 

The term artesian was originally applied only to wells which yielded 
a flow of water rising above the surface of the ground, but it is now 
frequently used for any water that will rise above the point where 
it is struck, indicating that it is under pressure or head. The ideal 
conditions for artesian circulation are two inclined layers of imper- 




Figure 6. — Diagram illustrating artesian conditions where water does not rise to the surface. 

vious material inclosing a layer of permeable material saturated 
with water for which there is no escape below the point where the 
water-bearing material is tapped. If the upper impervious layer is 
then penetrated in some manner, as by a drill hole, so that the satu- 
rated layer is entered at some point below the level at which the water 
naturally stands, the water will rise in the drill hole to a height 
determined by and nearly equal to the level at which the water stands 
in the water-bearing material. Figure 6 represents the conditions 
under which flowing wells may occur and under which the water will 
rise under artesian pressure to a certain level, but will not reach the 
surface. 

The level to which water will rise in the well will always be some- 
what lower than that of the water table in the permeable material, 
owing to the loss of head due to friction during the passage of the 
water to the well, and this difference in level will increase with 
increase of distance from the source of supply. 



OCCURRENCE AND RECOVERY OF GROUND WATER. 49 

The conditions en which artesian flow depends may be summarized 
as follows: 

1. A porous and permeable stratum capable of absorbing and 
transmitting large quantities of water. In certain localities planes 
of fracture may transmit the water rather than a porous stratum. 

2. Relatively impervious materials above and below, preventing 
the escape of water from the porous stratum. Such conditions might 
be realized by a bed of sandstone between two beds of shale or by a 
layer of sand resting on massive granite and overlain by clay. 

3. An exposure of the porous stratum where it may absorb water 
supplied either by direct precipitation or by percolation of waters 
falling on porous material above. 

4. An inclination of the water-bearing stratum so that gravity 
may force the water down and produce an artesian head. This 
inclination may be due to the manner of original deposition, but is 
ordinarily caused by a displacement of the strata after deposition. 

5. A lack of easy escape for the water at lower points than that 
where the porous material is penetrated, as the artesian head would 
be lost if the water had such escape. 

6. A sufficient precipitation and absorption to keep the porous 
material saturated and maintain the artesian head. 

Although these conditions are partly realized at many places in 
Connecticut, they are generally modified by many factors.. In the 
Connecticut Valley the relatively porous sandstone has a marked 
dip to the east, and it is not uncommon to find a stratum of sandstone 
confined between two layers of shale. However, these rocks are 
intersected by so large a number of fractures that the water which 
can not pass through the fine pores of the shale leaks through the 
jointed material, destroying the artesian head. At many places in 
Connecticut a number of springs occur in a relatively straight line, 
indicating the existence of a fracture plane along which waters are 
escaping from confinement below. The artesian waters, instead of 
coming to the surface through artificial wells, are escaping through 
the openings furnished by nature. Fuller a has shown that artesian 
conditions may occur in such uniform materials as sand, owing to the 
overlapping of the elongated sand grains. 

The fact that the ground water is in a state of continual motion, 
as shown by various experimental methods, implies that there must 
be some escape for the water at lower levels than that where it enters. 
Such natural escape may occur in a variety of ways. In a material 
of uniform nature, as sand, the surfaces of streams, lakes, and swamps 
represent the level of ground water at that point and the escape is 
due to slow seepage. Bodies of water fed in such a way are extremely 

a Fuller, M. L., Water-Supply Paper U. S. Geol. Survey No. 145, 1905, p. 41. 
463— irr 232—09 4 



50 



UNDERGROUND WATER RESOURCES OF CONNECTICUT. 



variable, increasing and decreasing in amount as the water table 
rises and falls, owing to varying weather conditions. The way in 
which such streams are fed is indicated in figure 5. 



SPRINGS. 



A large amount of the escaping ground water emerges at the sur- 
face in the form of springs that are usually rather constant in the 




Figure 7. — Diagram showing formation of a spring at the outcrop of an inclined impervious stratum. 

S, Spring. 




Figure 8.— Diagram illustrating manner in which spring may form at 
contact of soil covering and impervious rock below, when soil is re- 
moved by erosion, a, Point of emergence of the spring. 



amount of flow throughout the year. Such springs may represent 
an escape of artesian waters through fissures, as stated on page 49. 

Commonly they 
owe their existence 
to the presence of 
a stratum of pervi- 
ous material over- 
lying an impervi- 
ous layer (fig. 7). 
The water pene- 
trating the pervi- 
ous layer is prevented from moving downward through the imper- 
vious layer, whose slope it follows until it finally emerges at the sur- 
face at the contact of the 
two layers. 

Figure 8 represents a 
type of spring in which 
the top of a hill is capped 
by a layer of sandy soil 
resting on impervious 
rock. The ground water 
follows the rock surface 
until some opportunity is afforded for escape, when the water will 
emerge as a spring. 




Figure 9. — Diagram illustrating manner of formation of spring 
at contact of pervious formation and impervious formation 
when dissected. A, C, Impervious shale beds; B, porous 
water-bearing sandstone; M, top of saturated zone; X, point 
of emergence of spring. 



OCCURRENCE AND RECOVERY OF GROUND WATER. 



51 



Figure 9 represents the conditions where erosion has cut through the 
porous stratum and into the impervious layer, affording an easy escape 
for the ground waters. These diagrams represent two of the numerous 
ways in which springs may occur. Springs are usually seen issuing as 
streams rather than as a continuous seepage, both because the stream 
springs are more conspicuous and because if there is any considerable 
opening such as a joint crack the water will tend to concentrate in 
this open channel where the frictional resistance is least. 

AMOUNT OF GROUND WATER. 

It must be clearly understood that the amount of ground water 
is limited, as it depends on the amount of precipitation which is 
absorbed by the ground. The amount that escapes in the form of 
springs, though also dependent on the amount of precipitation, 



JltgJv tide 




v\\\ \\\\VV\ v\vs 



Figuke 10.— Diagram illustrating effect of tides on water table, a, Normal water table at high 
tide; b, normal water table at low tide; c, depressed water table during a dry season. 

varies relatively less than the precipitation. The amount of pre- 
cipitation, however, is variable, a dry season being marked by a 
lowering of the water table and a wet season causing a corresponding 
rise. The effect of these changes is always marked in shallow dug 
wells of the ordinary type, the water rising nearly to the top in 
winter and spring, whereas the same wells will be nearly or quite 
dry during the latter part of the summer. Springs also are affected 
to a certain extent by such seasonal changes, but the effect is rela- 
tively small as compared with wells. Variations in the level of the 
water table are also caused by barometric fluctuations, but though 
these variations may be sufficient to affect the amount of flow of 



52 UNDERGROUND WATER RESOURCES OF CONNECTICUT. 

springs, as shown by F. H. King, a they cause no permanent effect 
on the water supply. In wells near the coast fluctuations of the 
water table with the rise and fall of the tide are common, as the 
height of the sea water at high tide gives a slope to the water table 
differing from the slope at low tide. This is shown in figure 10. 

Neighboring wells will usually affect one another, as water can 
ordinarily be pumped from the wells faster than it can be supplied 
by the water-bearing material, and the water table is therefore 
depressed for a varying distance around the wells, so that heavy 
pumping of one well will cause the lowering of the water level in an 
adjacent well deriving its supply from the same source. It is not 
uncommon for an artesian well which had previously given a good 
flow to lose its flow entirely on the sinking of another well which 
happened to give an easier escape for the underground waters. As 
a rule the flow of artesian wells decreases with the lapse of time and 
the head gradually lowers, indicating that the well is exhausting the 
supply faster than it is renewed by precipitation, or, in other words, 
that the water table in the water-bearing material is undergoing 
continuous depression. 

TEMPERATURE OE GROUND WATER. 

When the water enters the ground it has a temperature corre- 
sponding to that of the atmosphere, but as it percolates downward 
it is affected by the temperature of the ground and within a very 
short distance from the surface acquires the temperature of the 
material through which it is passing*. In any region there is a 
certain depth at which the temperature is constant throughout the 
year and is practically the same as the mean annual temperature of 
the region. In Connecticut this depth is 50 to 60 feet, and the mean 
annual air temperature is 47°, so that waters at about 50 feet below 
the surface will have this temperature. Most of the Connecticut 
well waters come from much shallower depths, and consequently 
have temperatures above or below this average, depending on the 
season of the year. 

Below the level of constant temperature there is a fairly uniform 
increase of temperature with increase of depth, amounting to about 
1° F. for every 60 feet of depth. It is a common belief that the 
deeper the well the colder will be the water, but it will be readily 
seen that on this basis beyond a depth of 50 feet the deeper the 
well the warmer will be the water. This statement corresponds to 
the facts shown by the deep drilled wells of Connecticut, although 
in such waters there is a small change of temperature during the 
rise of the water to the surface. 

a Movements of underground water; Nineteenth Ann. Rept. U. S. Geol. Survey, pt. 2, 1899, pp. 75-77. 



OCCURRENCE AND RECOVERY OF GROUND WATER. 53 

CONTAMINATION. 

From what has been stated above, it is evident that ground water 
does not exist in pools or cavities in the rock and is not stationary. 
It has a movement in a definite direction, which can be determined 
for any given place. A velocity as high as 100 feet in twenty -four 
hours has been measured, but the common rates, even in sand, are 
only from 2 to 50 feet a day. (See p. 47.) The fact of the move- 
ment is undisputed and has an important bearing on health, for 
disease germs may be carried by water wherever it travels. No 
kind of rock or soil is proof against the transmission of ground water 
containing pollution. Fuller a has shown that water may traverse 
several miles of crystalline rock and may carry contamination 
through that distance. In a settled community too much emphasis 
can not be placed on the necessity of locating wells in positions 
where they are not liable to infection. The only safe way is to treat 
ground water as if it were a surface stream. No one would use 
water from a river a short distance below points of contamination, 
and no one should use water from wells where the downward slope 
of a ground-water table is such that the water might carry infected 
material. (See pp. 171-172.) 

a Fuller, M. L., Bull. Geol. Soc. America, vol. 16, 1905, p. 372. 



CHAPTER IV. 

GROUND WATER IN THE CRYSTALLINE ROCKS OF 
CONNECTICUT. 

By E. E. Ellis. 
INTRODUCTION. 

The laws governing the occurrence of ground water in unconsoli- 
dated material and in porous sedimentary formations are now gen- 
erally understood, but little has been written concerning the sources 
of supply for wells in the so-called crystalline rocks. The term 
"crystalline rocks" is used for those rocks whose component grains 
have crystallized into their present relative positions, in contrast with 
the sedimentary rocks, which were laid down under water and gener- 
ally consist of fragments of older rocks mechanically arranged. Under 
the head of crystalline rocks two main types may be distinguished — 
(1) igneous rocks, such as granite, diabase, gabbro, etc., which were 
once in a molten condition and which crystallized and hardened on 
cooling; (2) metamorphic rocks, such as schists and gneisses, which 
were originally either sedimentary or igneous but have been altered 
by metamorphic processes to their present form. 

Connecticut offers an exceptionally good field for an investigation of 
ground water in the crystalline rocks, as more than two-thirds of the 
State is underlain by rocks of this type (see fig. 11) and a large 
number of wells have been drilled in this area. 

LITERATURE. 

It seems necessary to dwell on the theoretical principles involved 
in the occurrence of ground water in crystalline rocks more largely 
in this paper than is customary in a report on underground water 
resources, because of the scarcity of previous information on these 
points. Accordingly a summary of the most important articles 
which have been written on such occurrences is here given. Many 
of these articles are contained in the discussions of the relation 
of circulating waters to ore deposits and to metamorphic changes. 
The principles involved, however, have been deduced for water circu- 
lation in general, both in rocks permeable because of their porosity 
and in rocks giving opportunity for circulation only through fracture 
planes ; the latter type corresponds to the crystalline rocks under dis- 
cussion. The theory as stated by Van Hise° considers that there 

a Van Hise, C R., A treatise on metamorphism: Mon. U. S. Geol. Survey, vol. 47, 1904. 
54 



GROUND WATER IN CRYSTALLINE ROCKS. 55 

are two general zones of water circulation — a zone below the level of 
ground water, where all openings in the rocks are filled with water, 
and a zone above the level of ground water, where the openings are 
but partly filled. He considers the extreme possible depth of cir- 
culating waters to be about 10,000 meters, which is the limit at 
which open fractures may exist. The circulating waters are con- 
sidered to enter the earth's crust at many points and as, owing to the 
force of gravity, they work downward, they tend to seek larger and 
larger channels, which offer less resistance to their flow, and finally 
to converge in some large channel and emerge at the surface at some 
point lower than that where they entered. Gravity is considered to 
be the primal force in producing this circulation. The chief objec- 
tion to this theory has been the assumption of a saturated zone below 
a certain level. Similar theories have been less fully brought out by 
Daubree, and by De Lapparent. 

Certain general statements regarding the occurrence of water in 
crystalline rocks and the procuring of water from joint planes are 
given by M. L. Fuller. 

In a paper on the water resources of a crystalline area in New 
Hampshire and Maine, George Otis Smith 6 has discussed the manner 
of occurrence of water in these rocks. He considers that the move- 
ment of the water is confined to stratification partings, joint openings, 
and less continuous passages, the main circulation being along master 
joints which are nearly horizontal. The circulation is slow owing to 
the constricted nature of the openings, and the water supplying wells 
is contributed from distant areas and is confined largely to trunk 
channels. The occurrence of certain flowing wells is attributed to 
constriction and cementation in the upper portions of the fractures, 
giving opportunity for hydrostatic pressure. 

J. A. Holmes c describes the occurrence of water supplies from the 
contact of fresh rock and the decomposed portion above in the cr}^s- 
talline rocks of North Carolina, but considers the undecomposed 
rock to be an uncertain source of supply. 

The only published discussion of well supply in the crystalline 
areas of Connecticut is by H. E. Gregory/ who gives certain statis- 
tics regarding the wells in this area. 

A number of records of wells drilled in crystalline rocks in New 
Jersey, Pennsylvania, New York, and Connecticut are given in the 
water reports of the New Jersey Geological Survey. 

A. Daubree/ in a treatise on subterranean waters, has paid par- 
ticular attention to various types of fractures that offer passage to 

a Occurrence of underground waters: Water-Supply Paper U. S. Geol. Survey No. 114, 1905, pp. 28-29, 39. 

b Water resources of the Portsmouth-York region, New Hampshire and Maine: Water-Supply Paper 
TJ. S. Geol. Survey No. 145, 1905, pp. 120-128. 

c Notes on the underground supplies of potable waters in the south Atlantic Piedmont plateau: Trans. 
Am. Inst. Min. Eng., vol. 25, 1896, pp. 936-947. 

<i Underground waters of Connecticut: Water-Supply Paper IT. S. Geol. Survey No. 114, 1904, pp. 78, 79. 

e Les eaux souterraines, 1887, pp. 150-157, 271-277. 



56 UNDERGROUND WATER RESOURCES OF CONNECTICUT. 

water. In considering rock fractures in relation to circulating 
waters he distinguishes three classes — "leptoclases," or small dis- 
continuous fractures such as occur in basaltic structure, dividing the 
rock into comparatively small fragments; "diaclases/' character- 
istic of all rocks and dividing the rock into polyhedrons by their 
mutual intersections; and "paraclases, " which represent such con- 
tinuous fractures as faults. The diaclases or joints are considered 
as planes extending in many places more than 300 feet laterally, and 
a joint series may extend with the same mean orientation for many 
miles. Their vertical extent is variable. In discussing the occur- 
rence of water in crystalline rocks Daubree notes the irregularity of 
occurrence and the general feebleness of springs from such rocks. 
He then states that however unimportant the movements of water 
may be near the surface, water-bearing fractures are still less acces- 
sible with depth, because they are less numerous and have tighter 
walls, and cites the experience of engineers in piercing the St. Gothard 
tunnel as proof. He also describes a series of three lava flows near 
Catania, which have absorbed an entire river into their fractures. 

Nordenskiold a has described a series of wells sunk at seven localities 
in Sweden on islands of igneous rocks such as granite, diorite, etc. 
These wells all obtained fresh water at a depth of 100 to 120 feet, and 
he considers the supply to be derived from horizontal fractures caused 
by the daily variations in temperature. He considers the most favor- 
able localities to be where vertical joints are lacking, but does not 
account for the origin of the fresh water. 

DISTRIBUTION AND CHARACTER OF THE CRYSTALLINE 
ROCKS IN CONNECTICUT. 

The general distribution of the crystalline rocks in Connecticut is 
shown on the map (fig. 11), where the State is seen to be divided into 
three sections, consisting of two areas of crystalline rock separated 
by an area of sandstone and trap which occupies a general depression 
between the higher crystalline rocks. The crystalline areas are well 
drained, although here and there lakes of glacial origin occur, and the 
stream waters contain unusually small amounts of mineral matter. 
The softness of the water has been an important factor in determining 
the location of many of the great woolen mills throughout the State. 

ROCK TYPES. 

The three types of crystalline rocks that cover the greater part of 
Connecticut beyond the limits of the central Triassic area are granite, 
gneiss, and schist, although near the western portion of the State there 
is a considerable area of dolomitic limestone largely changed to mar- 

a Sur une nouvelle espece de puits dans les roches granitiques de la Suede: Compt. Rend. Acad. Sci., vol. 
120, 1895, pp. 857-859. 



GROUND WATER IN CRYSTALLINE ROCKS. 



57 



ble. There are also several areas of more or less schistose quartzite. 
Cutting these formations are many masses of pegmatite and a few dikes 
of diabase or trap rock, and in the central Triassic area the trap occurs 
both as dikes and as surface flows standing in high hills and ridges 
above the general central plain. 

Granite. — There are many varieties of granite throughout the 
State, but they may all be distinguished by the characteristic granitic 
texture. The rock which throughout this discussion is considered 
as granite is in reality a granite gneiss — that is, a granite which has 
been subjected to metamorphism and has thereby acquired a gneissoid 
structure. The original granite nature is clearly evident and as gran- 




LEGEND 

mm wm 

Saudstoiie area Crystalline area 

10 1,5 20 25 miles 



Figure 11. — Map showing areas of limestone, sandstone, and crystalline rock in Connecticut. 

ite is a more popular name, this term is retained in the discussion, 
although on the map the designation granite gneiss is used. 

The rock is composed mainly of grains of quartz, feldspar, and mica, 
which are of fairly uniform size and easily distinguishable from one 
another. The rock is massive and will split about as readily in one 
direction as in another, except in joint planes. Locally schistose and 
gneissose phases occur even in a typical granite, giving one direction 
of easy fracture in the plane of schistosity. The main granite area is 
in the southern portion of the State and extends along or near a large 
part of the shore line. 

Along the coast from the New York state line to Bridgeport is an 
area of somewhat similar rock called granodiorite. This rock resem- 



58 UNDERGROUND WATER RESOURCES OF CONNECTICUT. 

bles granite but contains a much larger proportion of the black mica 
(biotite). At many places in this area it is highly schistose and may 
be split much more readily in one plane than in others. 

Gneiss. — The gneiss is a more variable rock than the granite, pre- 
senting very different characteristics even in adjacent areas and lack- 
ing the uniformity of texture of the granite. It may be distinguished 
by its banded or streaked appearance. It contains a large amount of 
feldspar and usually a considerable proportion of black mica or black 
amphibole, which, being present in greater amounts along certain 
lines than along others, gives the rock an appearance of alternating 
darker and lighter streaks. In some of the rock these streaks are de- 
veloped into even bands from one-half inch to 3 feet in width, which 
continue for several hundred feet with variations of less than an inch 
in thickness. The most conspicuous area of gneiss is in the south- 
eastern and eastern part of the State. Another large area consisting 
mainly of schist injected by granitic material occurs in the vicinity of 
Waterbury. 

Schist. — Although schist usually contains a large amount of quartz 
and feldspar its most conspicuous constituent is mica, which on casual 
inspection appears to constitute the bulk of the rock. A careful ex- 
amination will show that these mineral particles are much longer than 
they are wide and thick and that their longer axes lie in the same direc- 
tion. This is the direction of schistosity or rock cleavage, and the rock 
splits along this plane much more readily than in any other direction. 
Wherever there is an exposure of schist the tendency of the rock to 
split along the plane of schistosity together with the high angles at 
which these planes usually stand gives a jagged and serrated appear- 
ance to the rock surface. The parting plane is usually rather uneven, 
but in certain types of schist it is very smooth and shows a shining 
surface in the sunlight. Schist of this type called phyllite, is too fine 
grained to distinguish the separate constituent particles and closely 
resembles slate, being in fact, intermediate between a slate and a schist. 
Certain of the chloritic schists of Connecticut assume a similar aspect. 
Though nearly all the Connecticut crystalline rocks are characterized 
by the presence of garnet, this mineral reaches its largest and best de- 
velopment in the schists. 

The greatest development of the schists is beyond the western 
border of the Triassic area and in the area running from Middletown 
to the northeast corner of the State. 

Quartzite schist. — There are several areas of an extremely quartzose 
schist in the northeastern and northwestern portions of the State. 
This rock is composed entirely of quartz grains and is supposed to 
represent a quartzite completely metamorphosed to a schist. In the 
western part of the State recementation appears to have taken place, 



GROUND WATER. IN CRYSTALLINE ROCKS. 59 

resulting in an extremely indurated rock more nearly resembling a 
true quartzite. 

Pegmatite. — Traversing many of these rocks are dikes and irregular 
masses of pegmatite, which are white or very light in color and 
consist in great part of large crystals of white or pink feldspar with 
quartz and in places bunches of broad-leaved mica. This rock is 
usually called " feldspar" by drillers and quarrymen. 

Trap rock. — The trap rock is familiar to nearly everyone, and is 
easily distinguished by its dark color and fine-grained and compact 
texture. It occurs in the crystallized rocks as intrusive masses or 
dikes of material which has been thrust into older rocks. The 
external appearance of these dikes in the highland areas is closely 
similar to that of the traps of the lowland, and in composition the 
two rocks are identical. 

Limestone. — The limestone is softer than any of the other rocks 
considered; it may be readily scratched by a knife and will usually 
effervesce when acid is applied. It is ordinarily white or gray in 
color, and is the only rock considered in the present discussion 
which may be definitely classed as of sedimentary origin without 
careful study. It is usually dolomitic — that is, it contains a con- 
siderable proportion of magnesium carbonate and in many places has 
been metamorphosed to a genuine marble. 

DRILLING PRODUCTS. 

The marked characteristics of these rocks give equally charac- 
teristic products in drilling. In many places the drill will yield 
fragments that are large enough to show the general texture of the 
rocks. In others the drillings will all be in the form of rock dust. 
In general the granite drillings are even grained, with a large pro- 
portion of the white or pink minerals, quartz and feldspar, and the 
same character and color of material will be maintained for a number 
of feet. Gneiss gives a somewhat similar product but as a rule has 
a larger proportion of biotite (black mica) and the character of the 
drillings changes rapidly, usually every few inches. Schist is gener- 
ally softer and more readily drilled than either granite or gneiss, and 
the drillings contain a conspicuous amount of mica which occurs in 
larger particles than the other minerals. As in granite, the drillings 
maintain a fairly uniform appearance. The phyllite is usually a 
hard rock to drill, owing to its fineness of grain and the nearly 
vertical position of its cleavage at many places. Trap rock is 
considered the most difficult rock to drill, because of its hardness; it 
is readily distinguished from the other types. Limestone drillings 
are ordinarily white, and may be tested by adding acid or strong 
vinegar, which will produce an effervescence, owing to the escape of 
carbon dioxide. 



60 UNDERGROUND WATER. RESOURCES OF CONNECTICUT. 

DRIFT. 

Although in some places, particularly in the southern part of the 
State, the rocks above described are exposed at the surface, they are 
in large part covered with glacial deposits — till and stratified drift. 
The till occurs as a relatively thin layer over the rock surface both 
in valleys and on hills, and the valleys are filled with heavy deposits 
of stratified sand, gravel, and clay deposits resting upon the till and 
tending to form a flat valley floor. At many places the till has been 
eroded and the stratified deposits rest directly on the rock. The 
till deposits on the hills average about 15 feet in thickness, varying 
where present up to 60 feet or more; the valley deposits at many 
places are over 100 feet thick and average about 36 feet, although 
varying within very short distances owing to the irregularities of the 
underlying rock surface. These averages are made from the well 
records in the crystalline areas. 

In general, therefore, the hills have a configuration corresponding 
rather closely to that of the underlying rock surface, the minor 
irregularities of which are masked by the overlying drift. On the 
other hand, the valley bottoms are flat and a decidedly different 
topography would be shown if the sand and gravel deposits were 
removed. The general relation of the glacial deposits to the under- 
lying rock and to each other are indicated in figure 23. 

CONDITIONS AFFECTING OCCURRENCE OF WATER IN 
CRYSTALLINE ROCKS. 

INTRODUCTION. 

The occurrence of water in crystalline rocks is necessarily unlike 
that in most kinds of water-bearing sedimentary rocks, owing to the 
great difference of texture in the two types. In unmet amorphosed 
sedimentary rocks the pore space is usually large, running above 
20 per cent of the total volume in many sandstones and locally 
above 40 per cent. This means that such rocks will absorb an 
amount of water equal to one-fifth or even two-fifths of their entire 
volume. In the crystalline rocks there is little pore space between 
the constituent grains, which have crystallized into their present 
relative positions and therefore closely interlock with one another. 
Few of the granites have a porosity exceeding 1 per cent, and the 
average is 0.5 per cent or lower. a In gneissoid granites the propor- 
tion of pore space is about the same, and in slates it is less, averaging 
0.45 per cent or lower. Although in many limestones the porosity 
runs above 10 per cent, their metamorphosed equivalents — the 
marbles — have a porosity about equal to that of granite. 

a Buckley, E. R., Building and ornamental stones of Wisconsin: Bull. Wisconsin Geol. Survey No. 4, 
1898, p. 374. 



U. S. GEOLOGICAL SURVEY 



WATER-SUPPLY PAPER 232 PLATE 




A. VERTICAL JOINTS IN GRANITE. 




B. HORIZONTAL JOINTS IN GRANITE. 



GROUND WATER IN CRYSTALLINE ROCKS. 



61 



In such rocks as these, which absorb less than 0.5 per cent of their 
volume of water and contain less than 1 per cent of uniformly 
distributed pore space, the pores are mainly of subcapillary size and, 
though admitting water, allow little and exceedingly slow trans- 
mission. In many of the sedimentary rocks, on the other hand, the 
openings between the grains are of capillary or supercapillary size 
and give ready transmission to circulating waters. Therefore in 
the crystalline rocks the only circulation of water which has 
sufficient rapidity of movement to be of value as a source of well 
supply must be through joints and fractures developed subsequent 
to the crystallization. (See fig. 12.) 

JOINTS. 

A joint in rocks may be defined as an opening or fracture of great 
length and depth as compared with its width. Joints are produced 
by mechanical action 
which causes the rock to 
break into more or less 
regular blocks after it 
has hardened. They 
are usually attributed 
to some dynamic force 
that brings about move- 
ments in the earth's 
crust. They are ordi- 
narily called seams or 
cracks by drillers. 

Vertical joints. — The 
most common 'type of 
joints comprises those 
in planes approximat- 
ing a vertical position. 
(See PL I, A) Though 
there are many joints 
within 2 ° or 3 ° of verticality, the greater number deviate consider- 
ably from this position. A large number of measurements were made 
on the inclination of this type of joint in the crystalline areas of 
Connecticut, the average inclination of a series at any exposure being 
taken rather than a number of measurements on separate joints at 
the same exposure. The mean inclination, as shown by 75 obser- 
vations, was 74 ° from the horizontal. In only four observations did 
the inclination run below 40°, in 14 it was between 40° and 70°, in 
17 between 70° and 80°, and in 40 between 80° and 90°. It is evi- 
dent that in the Connecticut crystalline rocks the main jointing is 
between 70° and 90°. In several of the places where lower inclina- 
tions were observed the jointing was parallel to some structure plane 
in the rock. 









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Figure 12. — Diagram illustrating the manner in which a well 
obtains water by cutting joints. 



62 UNDERGROUND WATER RESOURCES OF CONNECTICUT. 

Horizontal joints. — In many of the rocks there is another set of 
joints which are very distinct from those of the vertical type, both 
in their degree of inclination and in their general nature. This set 
occupies an approximately horizontal position, in few places pitching 
more than 20°, and as a rule much less than this. (See PL I, B.) In 
general this joint structure follows the surface configuration of the 
rock, but here and there it pitches at a low angle in an opposite direc- 
tion to the slope of the hillside. In the most extreme cases of devia- 
tion from a horizontal position this jointing was found to be approx- 
imately parallel to planes of schist osity in the rock. This is well 
shown in the lower of the two gneissoid granite quarries near Maromas. 

In the further discussion of jointing, the names vertical jointing and 
horizontal jointing will be used for these two main types. 

Relation of rock type to jointing. — Both vertical and horizontal 
jointing are present in all the crystalline rocks, but occur in greatly 
varying degrees of development in the differing types. The hori- 
zontal joints are typically developed in the massive granites, where 
they are commonly very regular. They form the most striking 
feature of quarries in such rocks and constitute the plane of separa- 
tion called 1 1 bedding ' ' by the quarry men. In the gneissoid granites 
these joints are developed equally well, but their direction is deter- 
mined by the gneissoid structure in some places where that lies at a 
low angle to the horizontal. 

In the typical gneisses the joints are irregular and uncertain and 
occur only near tho surface; in the schists they are usually lacking, 
although here and there irregular and discontinuous fractures may 
be seen running in a nearly horizontal plane. Where such horizontal 
fractures occur in schists they are usually near the surface and very 
open. 

The vertical jointing is not confined to any particular rock type, 
but is developed throughout all consolidated formations, both sedi- 
mentary and igneous. The degree and nature of the development, 
however, vary not only with varying rock types, but also to a great 
extent in rocks of the same type in different localities. This differ- 
ence of development at the contact of rocks of two distinct types may 
consist of a mere tightening or closing of the joint on passing into the 
second rock, or of a difference in the number of the joints in the two 
rocks, indicating that some joints have stopped at the contact lines. 
Numerous instances of the former difference have been noted in the 
studies of ore bodies, and a good example on a small scale, typifying 
both differences, may be seen in the railroad cut just west of the 
station at West Haven, Conn. Here lenses and streaks of extremely 
schistose and slaty rock occur with similar layers of compact diabase 
several feet in thickness. The diabase is completely traversed by 



U. S. GEOLOGICAL SURVEY WATER-SUPPLY PAPER 232 PLATE II 




A. JOINTS IN SCHIST AND METAMORPHOSED DIABASE. 




B. JOINTED AND FISSILE SCHIST. 



GROUND WATER IN CRYSTALLINE ROCKS. 63 

joints and seams, some of which stop abruptly at the contact with 
the schistose rock, while those which continue across the schist are 
relatively tight. A similar occurrence on a larger scale may be seen 
on the north bank of Housatonic River, 3 miles above Derby, where a 
schist lies above a heavy pegmatite. It is impossible with present 
evidence to say what will be the rule in this respect at the contact 
of a schist and a granitoid rock, but it seems probable that in most 
such places the joints will become tighter and less numerous in passing 
from a granitoid to a schistose rock. (See PL II, A, B.) 

Joint direction. — Any individual joint maintains a fairly constant 
direction with a few small curves, and here and there the same direc- 
tions of prominent jointing will remain fairly constant over a con- 
siderable area, as shown by the observations of Hobbs a in the Pompe- 
raug Valley, where he found four major directions of jointing. Where 
there is a particularly well-developed joint set the series may maintain 
the same general direction for long distances. 

In a series of observations throughout the crystalline areas of the 
State it was found by the writer that a much larger proportion of 
joint systems ran in a northwest-southeast direction than in one 
northeast and southwest. However, for particular localities the direc- 
tion of jointing can be determined only by local observations. 

Structure planes. — Of secondary importance to the joints as regards 
water supply is the presence of structure planes, such as schistosity 
and gneissoid banding in the rocks. In rocks exhibiting these 
features there has been more or less fracturing parallel to the structure 
planes, which have an average inclination much lower than the joints. 
The planes of schistosity dip at all angles, but for any single formation 
there is usually some dip which is more constant than others. Obser- 
vations on these formational dips in Connecticut show them to be 
quite as commonly below 45 ° from the horizontal as above that angle, 
whereas, as previously shown, most of the joints, exclusive of the 
horizontal joints, have greater dips than 75°. 

The fracturing parallel to the schistosity may consist of rather 
widely spaced and relatively open fractures or of small discontinuous 
breaks an inch or less apart, producing a structure known as flssility. 
Whatever the nature of these fractures, they will average a lower 
inclination than joints, although in some rocks, as in the chlorite 
schist and phyllite west of New Haven, they are nearly vertical. 

Variation in jointing. — In the schists and similar rocks, with a 
marked schistose structure, such as the schistose granodiorite along 
the coast east of Greenwich, there is usually one direction or system 
of jointing that is more prominent than any other. This main system 

a Hobbs, W. H., The Newark system of the Pomperaug Valley, Connecticut: Twenty-first Ann. Rept. 
U. S. Geol. Survey, pt. 3, 1901, pp. 7-162. 



64 UNDERGROUND WATER RESOURCES OF CONNECTICUT. 

is, as a rule, accompanied by a wider spaced and less well developed 
series of joints intersecting the main series at high angles. In the 
schistose granodiorite the jointing is well developed, rather closely 
spaced, and very uniform in direction. In the schists the joints 
maintain a fairly uniform trend, but are commonly very tight, and 
in much of the rock die out within short distances. In most ex- 
posures one or two distinct series of joints can be distinguished, and 
many small irregular fractures connecting the main joints occur near 
the surface, but disappear at relatively shallow depths. 

In the granitoid rocks the vertical joints are generally more open 
and continuous than those in the schistose rocks, but usually lack 
their characteristic regularity of arrangement in series and are ordi- 
narily more widely spaced. Although in many of these rocks there 
is one set of joints with a general parallel direction, even in the joints 
which may be classed in the same series there may be a variation of 
10° to 20° in direction, and other vertical joints may intersect these 
with no regularity of arrangement with reference to each other. 
This is the usual occurrence of jointing in the Connecticut crystalline 
rocks of this class, but in certain places two, three, or even four dis- 
tinct sets of joints may be distinguished. 

The limestones of the State are even more irregularly fractured 
than the granites and the fracturing is usually so close as to prevent 
the use of the rock as building stone. Joints cut these rocks at all 
angles, and the general shattering has produced more open space 
than in any other type of rock which might be classed as crystalline. 

No general conclusions on the occurrence of vertical joints in the 
crystalline areas of Connecticut will hold for every portion, as there 
is great variation in their occurrence within short distances, even in 
the same formation. On the other hand, the horizontal joints have 
a very uniform mode of occurrence for all the granitoid rocks. They 
are approximately parallel to the rock surface, except where influ- 
enced by local factors such as structure planes, and are spaced at 
fairly uniform distances from one another. They are everywhere 
curved or wavy and intersect one another at varying intervals, 
dividing the rocks into a series of approximately horizontal wedges 
with curved faces. The principal variation is in the closeness of 
these intersections. In some places the horizontal joints intersect 
one another every 20 or 30 feet; in others they run parallel to one 
another for 100 feet or more. In general the horizontal jointing is 
more regular, though not necessarily better developed, where the 
amount of vertical jointing is small. A good example of this may be 
seen in the gneissoid granite quarry at Monson, Mass., where there is 
an excellent parallel horizontal jointing but vertical joints are almost 
lacking and except at the immediate surface are filled with vein 
material. 



GROUND WATER IN CRYSTALLINE ROCKS. 65 

FAULTS. 

Faults may be considered as extreme types of joints in which there 
has been movement of one wall of the joint plane past the other. 
The work of Hobbs, Davis, and others has shown that there has been 
a considerable amount of faulting in Connecticut, and it is not un- 
common to find strongly marked shear zones, indicating slipping in 
the crystalline rocks. These are rather rare phenomena, however, 
and are seldom encountered in well drilling; accordingly they will be 
treated simply as special cases of jointing. They are probably very 
important as channels for spring waters, although it is extremely 
difficult and generally impossible to ascribe any particular spring to 
a fault plane. 

CIRCULATION AND STORAGE OF WATER. 

The circulation of water in the crystalline rocks, being confined to 
openings of the sort discussed in the foregoing pages — that is, those 
having great length as compared with their thickness — is necessarily 
limited by the abundance of these planes of parting, by their degree 
of opening, and by their intersection of one another; and there are 
many modifying factors, such as local entrance conditions for surface 
waters, local textural variations in the rock, intrusions and inclusions 
of other rocks, and the restraining effect of overlying glacial drift. 

INFLUENCE OF JOINTS AND OTHER OPENINGS. 

Spacing of vertical joints. — The vertical joints, which are the im- 
portant water carriers, have no regularity of spacing even in the 
same rock. These joints are much more closely spaced in natural 
outcrops, owing to the influence of weathering, and in railroad cuts 
where there has been heavy blasting than in quarries where the natural 
conditions prevailing in the rock below the surface are exhibited. In 
such natural exposures the spacing of joints was found to vary from 
a fraction of an inch up to 200 feet or more. The extremely close 
jointing occurs only in sheeted or shear zones which vary from a few 
inches to 2 feet in width, and these sheeted zones are a considerable 
distance from one another. Instances of such close sheeting as to 
give a spacing of 1 inch are exceptional, and are found in relatively 
few exposures. The same general occurrence on a larger scale, how- 
ever, is typical of vertical jointing. In every quarry observed in 
Connecticut where jointing is developed over a considerable area the 
joints were found to be much more closely spaced at certain points 
than at others, constituting a series of zones of close jointing separated 
by intervals in which the distances between joints are much greater. 
These zones of close jointing vary from 1 foot to 15 feet in width and 
the joints making up the sheeted areas are spaced from 3 inches to 
463— irr 232—09 5 



66 UNDERGROUND WATER RESOURCES OF CONNECTICUT. 

2 feet apart. Purington a describes a similar but more regular occur- 
rence in a Colorado mine where, along the side of a drift, fissures 30 
feet apart become nearer and nearer together until they are only 

3 or 4 inches apart, forming a sheeted zone, beyond which the intervals 
gradually increase. 

A number of observations on joint series in the Connecticut crystal- 
line rocks indicate that at the places where jointing is well developed 
the average spacing is between 3 and 7 feet. It is very difficult to 
form an estimate of the average spacing for all rocks, however, for 
in some localities, as in the quarries at Monson, Mass., and Sterling, 
Conn., there are exposures of several acres where the rock has been 
quarried, and not more than three or four open joints can be dis- 
tinguished in the entire quarry, giving a spacing of at least 100 feet. 
Here and there older joints may be distinguished which have been 
filled with vein material, but these can yield no water under present 
conditions. 

If it were supposed that all the vertical joints were placed in parallel 
planes, both major and minor series, it is probable that the average 
spacing would not be less than 7 feet to a depth of 50 feet from the 
surface. The average spacing between vertical joints of the same 
series for the crystalline rocks, exclusive of trap and limestone, is 
more than 10 feet for this same zone of 50 feet from the surface, as 
shown by field observations, and the study of well records indicates 
that this is not far from the average spacing for all joints to a depth 
of 100 feet. 

Spacing of horizontal joints. — -The horizontal joints present much 
greater regularity of spacing than the vertical joints. They are 
apparently surface phenomena and diminish in number rapidly with 
increasing depth; it is probable that they do not exist at a depth of 
200 feet. For the first 20 feet below the surface these horizontal 
joints average 1 foot apart, for the next 30 feet they average between 

4 and 7 feet, and for the next 50 feet they are much more widely 
spaced, being from 6 to 30 feet or more apart. 

Continuity of horizontal joints. — The length of individual hori- 
zontal joints rarely exceeds 150 feet, but owing to their intersection 
of one another they may constitute a continuous opening several 
hundred feet long, which would have the form of a curved sheet 
approximately parallel to the hill slope, each lower sheet having less 
curvature than the one above. They are probably better developed 
on the hills than in the valleys, as the pitch of the joints is usually 
less than the slope of the surface, which consequently cuts across 
the joints. Moreover, as they are more widely spaced with depth 
the horizontal joints that cross the valleys are widely spaced. 

a Purington, C W., Preliminary report on the mining industries of the Telluride quadrangle, Colorado: 
Eighteenth Ann. Rept. U. S. Geol. Survey, pt. 3, 1898, pp. 765-769. 



GROUND WATEK IN CRYSTALLINE ROCKS. 67 

Continuity of vertical joints. — There are two directions in which 
vertical joints may have great length — vertically, or along their dip, 
and in the direction in which they cut the surface. No mathematical 
relation between these two directions has been determined, but it 
has been assumed in the study of ore deposits that a fracture will 
have about as great extent along the dip plane as along the strike 
plane. The degree of continuity is very uncertain owing to the 
difficulty of direct observation on either the entire length or the 
depth of any joint, and to the fact that a joint may exist with its 
two sides so closely pressed together that the fracture is not apparent 
to the naked eye. It is certain that some joints are far more con- 
tinuous than others and that many die out within very short distances 
both vertically and laterally. Faults have the greatest continuity 
and may extend for several miles across the country, or even for 
tens of miles. The sheeted zones of closed jointing are probably 
almost as continuous as faults, and their dimensions should be 
measured in hundreds of feet. Where there is a well-defined series 
of parallel joints the prominent joints may extend for several hundred 
feet, while the minor intersecting joints will be much shorter. 

Fissility and schistosity openings. — The circulation of water as 
determined by structure planes has not been discussed up to this 
point because the evidence is not as clear as in the case of joints. 
Although it is probable that the absorptive capacity of a schist 
would be greater than that of a slate, owing to the larger size of the 
grains, the porosity would still be too small to allow any circulation 
in the pores. In a crumpled schist there are probably small open- 
ings between the folded laminae, but these must be discontinuous 
and would not a^low sufficiently rapid circulation for well supply. 
However, there are nearly everywhere fractures of considerable 
extent parallel to the schistosity, but with much less regularity of 
occurrence than the joint planes in the same rock. These fractures 
also are much less continuous than joints and die out within short 
distances. 

In such discontinuous fractures the circulation would be com- 
paratively slow, but sufficient for well supply. Small springs issue 
from such fractures at many places, as along the east bank of 
Connecticut River above Hadlyme Landing. These fractures are 
much more numerous near the surface, particularly where the dip 
of the schistosity is in a low plane, and become tighter and less 
abundant with increasing depth. 

Intersection of fractures. — It has been shown that the main circu- 
lation of water available for well supplies in crystalline rocks is along 
jointing planes, and it will be shown later that some joints carry a 

a Ransome, F. L., Economic geology of the Silverton quadrangle, Colorado: Bull. U. S. Geol. Survey No. 
182, 1901, pp. 61, 62. 



68 UNDERGROUND WATER RESOURCES OF CONNECTICUT. 

greater amount of circulating water than others. It is evident that 
the intersection of joints with one another is a very important 
factor in determining the degree and direction of the underground- 
water circulation. 

The manner of occurrence of joints indicates that such intersection 
may be found in every possible direction, but that there will be 
much better connection in some of them than in others. In the 
granitoid rocks, where the vertical joints have little regularity of 
arrangement and therefore intersect one another at many points, 
and where the horizontal joints are nearly universal, there is a 
thorough connection between the various fractures of the upper 
zone in which the horizontal joints occur. In the schists and schis- 
tose gneisses, in which the joints are usually more regular in arrange- 
ment and in which the horizontal joints are poorly developed, the 
connection between the various joints is less complete. In these 
schistose types, as in the granitoid rocks, there are invariably cross 
joints connecting the main systems, but they are commonly con- 
siderable distances apart and are tighter than the main joints, so 
that the opportunity for lateral transmission of water from one 
joint to another parallel joint is less than for longitudinal trans- 
mission along the main joints. The connection of the small and 
discontinuous fractures in the planes of schistosity is much poorer 
than that of the joints. 

Opening of joints. — The degree of opening between the walls of 
joints is exceedingly variable and very difficult to measure. At the 
immediate surface many joints have an opening of half an inch to 2 
inches, or even much greater. This wide opening is due to various 
weathering and mechanical agencies, which act only near the surface, 
and consequently is not found at depths below which these agents act. 
In an artificial cut, such as a quarry wall, many of the joints which 
may be open half an inch at the surface are too tight to admit a 
knife blade at a depth of 25 feet. 

The joints at 30 feet below the surface may have only one-twentieth 
the opening that they have at the surface, but the same proportionate 
tightening will not continue at lower depths, although it is certain 
that the greater the depth the greater must be the tendency of joints 
to close, owing to increased pressure and to the smaller opportunity 
for lateral expansion below the level of minor topographic relief. 

The closing with increasing depth is, of course, a measure of the 
vertical continuity of the joint, and it seems very probable that there 
is a direct relation between vertical and longitudinal continuity. 
Accordingly there is a great variation in the depths at which different 
joints close; the smaller joints close at moderate depths, but the 
larger joints continue to varying greater depths according to their 
importance. 



GROUND WATER IN CRYSTALLINE ROCKS. 69 

If the above statement holds true, the closing of the joints produces 
not only a tightening with increasing depth, but also a decrease in 
number or a widening of the space between joints. This principle 
applied to the vertical joints is closely analogous to the tightening 
and increase of spacing of the horizontal joints with increasing depth, 
which may be observed at nearly any granite quarry, although the 
causes producing the two types may be different. 

The application of this principle in the drilling of wells is of the 
utmost importance, as it is frequently asserted that water can always 
be obtained by going deep enough, whereas the deeper the well the 
less the chance of striking fractures, which are the only passages 
permitting water transmission in crystalline rocks. It is evident 
that, owing to the closing with depth, there will be a much greater 
circulation in the upper half than in the lower half of any individual 
joint. 

Though many of the joint openings are supercapillary in size, 
most of them are probably of large capillary size. The upper limit 
of capillary sheet openings is about one one-hundredth of an inch, 
which gives an opening of appreciable size, but in a freshly quarried 
wall the greater proportion of the joints have manifestly less width 
than this. A rough estimate of the degree of opening of joints may 
be made from the yield of wells in the crystalline rocks, which average 
about 17 gallons a minute, although the greater number give less 
than 15 gallons a minute. The average well intersects between three 
and four joints, and this number of saturated joints would supply 
much more than the average yield of the wells if the openings were 
appreciably larger than capillary size. These openings, however, 
must be toward the upper limit of capillarity in order to yield 10 to 15 
gallons a minute. Some wells undoubtedly pass through openings of 
much greater width than 0.01 inch, and nearly every well driller can 
cite several instances when his drilling tools have suddenly dropped 
several inches. Although the driller usually considers the sudden 
fall of the tools to indicate an open crevice, the probability is that 
no actual open space exists, but that a fracture has been encountered 
in which decomposition has softened the rock walls to such an extent 
that the material offers little or no resistance to the heavy drill. 
Nearly every quarry in the crystalline areas of Connecticut gives 
examples of such decomposed strips bordering joints, but such an 
occurrence as an opening wider than a fraction of an inch in crystal- 
line rocks, except at the immediate surface, is practically unknown 
to quarry men. 

It is probable that openings of considerable size occur along fault 
planes, but faults are relatively few as compared with joints, and 
there is small chance of a drill hole penetrating them. Some of the 
wells of larger capacity may derive their water from such fault 



70 UNDERGROUND WATER RESOURCES OF CONNECTICUT. 

openings, although more probably it comes from a closely sheeted 
zone. 

Number of contributory joints. — The number of fractures supplying 
water to a single well varies greatly in different wells. In some 
wells the greater part of the water appears to come from a single 
opening; in others the water comes in slowly from a large number 
of openings. In the average well there are from one to four horizons 
at which the principal supplies of water are obtained, although the 
yield from one of them is usually greater than that from all the others 
together. This is particularly true of the wells from 200 to 300 feet 
deep, in which the principal source is usually very close to the bottom 
of the well. 

From the character of the fractures in the varying rocks it seems 
probable that the wells in gneiss and the deeper wells in granite 
derive their main supplies from one or two comparatively large open- 
ings, but that in the more schistose rocks the fractures contributing 
water are more numerous but less open. In the upper portions of 
the wells in granite the horizontal joints contribute a series of small 
supplies below the point where the water level is struck. 

If an average inclination of 70° from the horizontal and an average 
spacing of 10 feet is assumed for the vertical joints for the upper 200 
feet of rock, each well 200 feet in depth would intersect seven joints. 
This is probably not far from the average for all the wells, exclusive 
of the small and discontinuous fractures near the surface. Below 200 
feet the average number of joints intersected would be somewhat 
decreased for the next 100 feet and greatly decreased at lower depths 
than 300 feet. It is evident that in some localities the joints are 
much more closely spaced than in others, that locally they are highly 
inclined and elsewhere lie at low angles, and that all these factors 
modify the number of fractures which a well intersects. 

WATER LEVEL. 

If the fractures were all equally open and had complete connection 
with one another, there would be a zone of saturation in the crystal- 
line rocks and the upper surface or water table of this saturated zone 
would follow rather closely the shape of the rock surface, as in sand 
or other homogeneous porous material. Under such conditions the 
water in adjacent wells should rise to the same level. In homoge- 
neous sands the upper limit of the saturated zone is called the water 
table. In describing the occurrence of water in joints the term 
" water level" will be used to indicate the upper limit of the satu- 
rated portions of the joints. 

Observation shows that the fractures are of greatly varying degree 
of opening, and that although most of them are connected with one 
another in some way the connection is much better in some places 



GROUND WATER IN CRYSTALLINE ROCKS. 



71 



than in others. It is to be expected that under such conditions water 
will rise to different heights, even in joints which are close together, 
when there is no connection or very poor connection between them. 
As a typical instance of such variation may be cited the wells drilled 
for the Fitch Home for Soldiers at Noroton Heights, Conn. One well 
was drilled to a depth of 425 feet in the bottom of a small valley, 
resulting in a flow of 4 gallons a minute that rose more than 7 feet 
above the surface. A second well was drilled 130 feet away and at 
an elevation only 4 feet higher, to a depth of 503 feet, and in this 
well the water rose only within 15 feet of the surface. Both wells 
passed through about 12 feet of hardpan. The difference of pressure 
head in these wells, only 130 feet apart but evidently deriving their 
water from different fractures, is therefore more than 18 feet. Both 
these wells give heavy yields on pumping and the pumping of the 
second well does not affect the flowing well, although it lowers the 
level of the water in an old drilled well higher on the hillside. Similar 
occurrences have been noted at other places, even in wells less than 
100 feet deep. 







Vertical scale 











250 


500 Feet 











Horizontal scale 
2 




A 


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50 


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4 Miles 


60^v£ 


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-150 


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48 


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S5 "^Cj^p^ 


200 




20 




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J 253 




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24-4- 





Figure 13. — Sketch showing relation of water level to topography, a, Surface of ground; b, line indi- 
cating height at which water stands in wells; c, rock surface. 

Although there are local irregularities in the water level in the 
crystalline rocks, such as that just described, the general surface of 
the saturated zone still follows the topography, as is shown by the 
heights at which the water stands in the various wells. (See fig. 13.) 
The following table indicates the relation of the level at which the 
water stands in the wells to the surface of the rock: 

Relation of water level in wells to surface of rock. t 



Position. 



Number 

of wells 

averaged. 



Percentage with water level- 



Below 
rock 

surface. 



Above Even 

rock with rock 

surface. surface. 



Hills.... 
Valleys. 
Slopes . . 



61.9 
12.5 
48.5 



26.2 
87.5 
40.0 



11.9 

11.5 



72 UNDERGROUND WATER RESOURCES OF CONNECTICUT. 

It is thus evident that on the hills the water tends to stand below 
the rock surface, but that in the valleys it is under sufficient hydro- 
static head to rise above the rock surface and under favorable con- 
ditions to cause flowing wells. 

At many places on the hills the tendency of the water level in 
the crystalline rocks to stand lower than the rock surface gives 
rise to an unsaturated zone immediately below the drift, although 
the lower portion of the drift itself may be completely saturated 
and furnish excellent supplies for comparatively shallow dug wells 
of large diameter. The existence of such an unsaturated belt is 
believed to be due to the facts that the movement of water in certain 
places is more rapid through the upper fractured portion of the 
rock where the joints are open than through the relatively small 
capillary openings of the drift and that the water, having opportunity 
to escape from the rock crevices at some point lower than the enter- 
ing point, is carried away down to a certain level faster than it is 
furnished. In some localities, however, where the fractures do not 
allow escape at lower levels, the water table of the drift and of the 
rock may be the same; that is, in wells deriving water from rock 
seams the water may rise to the same level as in open wells in the 
drift above. However, owing to the generally rapid movement in 
fracture planes the general water level tends to approach a flatter 
plane in crystalline rocks than in porous materials like sand, where 
there is greater frictional resistance to water flow and where the 
effect of capillary flow is greater. 

The term "water level," as used in reference to the depth below the 
surface at which water stands in the openings of crystalline rocks, 
in its broad sense, implies a surface with much smaller differences 
of elevation than the water table of a sandstone area having similar 
topographic relief, but with much greater minor irregularity, owing 
to the great variation in the water channels. The larger fractures 
extending for long distances usually have some outlet to the surface, 
but in many of the smaller joints the water passes from one joint to 
another with no surface outlet. The fast flow in the larger joints 
lowers the level of the water in these and connected joints below 
that in neighboring unconnected joints having poorer outlets. Even 
in a connected series the water level will have different heights in 
joints of varying opening, owing to the faster flow in the more open 
joints, where friction is less. 

DIRECTION OF CIRCULATION. 

The movement of water entering any joint above the point where 
it is saturated with water will be mainly vertical along the dip or 
inclination of the joint. The circulation below the water level in 
any joint is both vertical and lateral. The lateral motion, along the 



GROUND WATER IN CRYSTALLINE ROCKS. 73 

strike of the joint, predominates, owing to the fact that the length of 
the outlet or outlets for any particular joint is much smaller than the 
total length of the joint. Any connected series of joints there will 
manifestly have a very complex circulation, but the main circulation 
will be toward and along the fractures having the largest openings and 
the nearest outlets, and in these fractures the general movement will 
be in the direction in which the land slopes. 

DECOMPOSITION AS A MEASURE OF CIRCULATION. 

The relative importance of various joints in the water circulation 
is indicated by the decomposing effect of the water on the walls of the 
fracture planes. The oxidizing surface waters carrying carbon 
dioxide and organic acids naturally react on the minerals in the rock 
walls, the action being indicated in some places by a mere reddish- 
brown staining of the joint sides and here and there by a breaking 
down of the mineral particles, giving rise to a disintegrated border 
along the joint plane. There is a great difference in the amount of 
this weathering, even in joints which may be adjacent members of 
the same series, indicating that some joints are heavier water carriers 
than others of the same age, probably owing to greater opening and 
in some of them to better entrance conditions. The areas of greatest 
decomposition are along the sheeted zones, and next along the most 
continuous vertical joints, and in these fractures the weathering 
extends down to the limit of observation, with no apparent change. 
In the minor joints the weathering effects are less conspicuous and 
usually appear to the observer as mere discolor ations, extending from 
half an inch to 3 inches or more on each side of the joint plane and 
becoming less marked with increasing depth. 

As a rule the horizontal joints of the granitoid rocks show less 
weathering than the minor vertical joints. Though usually discolored 
and weathered near the surface, the walls of these joints are commonly 
unaltered at a depth of 20 feet. However, where the horizontal 
joints are cut by a prominent weathered vertical joint, the weathering 
effect extends along the adjacent horizontal joints to a very marked 
degree, diminishing in amount with increasing distance from the verti- 
cal joint. This feature is well shown in the granite gneiss quarry of 
the Rhode Island Brown Stone Company, 1J miles west of the railway 
station at Oneco, Conn. At this quarry a heavy discoloration extends 
along the flat joints for a distance of 25 feet from a vertical joint, 
gradually diminishing in intensity. Occasionally a flat joint is found 
which is weathered throughout its exposed length. (See PL III, B.) 

In the sheeted zones it is common to find a strip of disintegrated 
material from 1 to 6 inches in thickness and in the large single verti- 
cal joints similar but narrower bands of disintegrated rock occur. 



74 UNDERGROUND WATER RESOURCES OE CONNECTICUT. 

Through such material as this a large amount of water can pass with 
comparative ease. 

If the degree of decomposition along joint planes is taken as a cri- 
terion of the amount of circulation along the joints it would appear 
that the circulation is mainly along the large vertical joints, next along 
the minor vertical joints, and in small amounts along the horizontal 
joints. Although this statement is probably true as to the propor- 
tionate amounts of circulation it does not mean that the unweathered 
vertical or horizontal joints are dry. The probability is that the 
lower horizontal joints are saturated with water, but that owing to 
the relatively flat planes in which they lie and their tendency to 
tighten at their intersection with one another, the water has a very 
feeble circulation. 

The horizontal joints are probably much younger than the vertical 
joints and weathering has had less time in which to act, but the fact 
that some are weathered more than others indicates that even in these 
joints, which are manifestly of the same age, some offer better condi- 
tions than others for water circulation. 

STORAGE OF WATER. 

The wells in the crystalline area of Connecticut are remarkably 
constant, showing little variation in yield or depth of water, either 
annually or through a period of years. In some the yield has 
increased since the well was drilled and in a few it has decreased, but 
most of the wells have shown no appreciable change. The level to 
which the water rises in the wells shows nearly as great constancy 
as the yield, although in the shallower wells the water level varies 
somewhat with seasonal variations in rainfall, and in some of the 
deeper wells a lowering of water level has been noticed in unusually 
dry years. These fluctuations are most conspicuous in wells of 
small yield. In nearly all wells the water level is lowered to a greater 
or less extent on pumping, until by this lowering a sufficient increase 
of head is obtained to give an increased rapidity of flow, which will 
furnish a yield equal to that pumped out. When the pump is stopped 
the water will gradually, or in some wells very rapidly, rise again to 
its normal level. Minor fluctuations are probably more common 
than is reported, as changes in level are not readily noticed in covered 
wells. However, it is evident that there must be a very constant 
supply of underground water to maintain so constant a level in the 
wells. 

The total average yearly rainfall in Connecticut is 46.89 inches, 
rather uniformly distributed throughout the year, and this uni- 
formity of precipitation will, under natural conditions, with no 
artificial removal of water, give a fairly constant level for ground 
water in the rocks. If 25 per cent of this amount of rainfall is 



GROUND WATER IN CRYSTALLINE ROCKS. 75 

assumed to be absorbed by the rocks — undoubtedly a considerably 
higher percentage than is actually absorbed — the total amount 
absorbed by an area of rock 100 feet square is 9,768 cubic feet, or 
73,260 gallons. A well pumping 15 gallons a minute, which is about 
the average yield of wells in the Connecticut crystalline rocks, would 
draw out this amount in 81.4 hours. A well of this capacity pumping 
for 300 days during the year for one hour a day would withdraw an 
amount of water equal to 25 per cent of all the water falling on an 
area within a radius of 108 feet around the well. Probably 10 per 
cent of the precipitation more nearly represents the proportion 
absorbed by the rock than 25 per cent, and if so a well pumping at 
the rate above indicated would draw all the water on an area more 
than twice as great. When it is considered that some wells are 
pumped at the rate of 30 gallons a minute for ten hours a day through- 
out the year, it is evident that a single well may drain a very large 
area of all the water it absorbs. 

With an average spacing for all fractures of 5 feet and an average 
opening of 0.01 inch, the saturated fractures in 1,000,000 cubic feet of 
rock, equivalent to a depth of 100 feet for a surface area 100 feet 
square, would hold 833 cubic feet of water, which a well with a capac- 
ity of 15 gallons a minute could pump out in seven hours if there 
were no renewal of the supply. 

These figures are sufficient to indicate that the area contributing to 
any one well must be very large to maintain a constant level for the 
water in the well. Owing to the shape of joints and the manner in 
which they intersect one another this contributing area will be in the 
form of a number of long and comparatively narrow intersecting 
belts, and the well will draw water from very long distances. Wells 
on islands surrounded by salt water have been successful in obtain- 
ing supplies of fresh water, but they are usually moderate in yield 
and frequently somewhat contaminated by salt water, so that as a 
general rule fresh water obtained in these locations consists of that 
which has fallen on the island itself. Fuller, a however, cites a well on 
Fishers Island, 3 miles from the Connecticut coast, that penetrated 
281 feet of unconsolidated gravel, sand, and clay in which salt water 
was found, and obtained fresh water in the crystalline rock below. 
No outcrops of crystalline rock occur on this island, and it seems 
clear that the fresh water must have come through the joint openings 
from the mainland 3 miles away. The water is evidently held in the 
rock openings by the restraining covering of clay above the rock. 

As the head in all the wells is fairly constant, it is evident that 
the yield in any well is proportional to the number and opening of the 
fractures contributing water. As the heaviest yields are derived 
from the most open joints, and as these joints are the most continuous 

a Fuller, M. L., Geology of Fishers Island: Bull. Geol. Soc. America-, vol. 16, 1905, p. 372. 



76 UNDERGROUND WATER RESOURCES OF CONNECTICUT. 

(see pp. 66-67), the following relation holds: The yield of water from 
a joint is proportional to its continuity, which depends partly on the 
number of intersecting joints and which consequently determines the 
area contributing to the wells. If this relation is true, and the yield 
is proportional to the contributing area, it follows that there will be no 
permanent change of head in the well until the amount withdrawn 
by the well is greater than the annual absorption of rainfall throughout 
the contributing area. This statement may be made in another way : 
When a small amount of water is pumped from a well the contributing 
area is small, but as larger amounts are pumped the contributing area 
is increased and the more remote connecting joints give their con- 
tribution to adjust the difference of level caused by the tendency 
toward depressions of the water level in the immediate vicinity of the 
well. Owing to frictional resistance to flow there will, of course, be 
some depression at this point, but it is probably relatively small. 
When the amount withdrawn by the well annually is greater than the 
amount annually absorbed by the contributing area the water level 
in each connecting joint is lowered and a permanent lowering of the 
water level results. As any lowering of the water level means a loss 
of head for the well, and as the head determines the rapidity of flow 
into the well, it is evident that when the water level is lowered the 
yield of the well will immediately decrease. 



GROUND WATER IN CRYSTALLINE ROCKS. 



77 



TABULATED WELL RECORDS. 

The following tables, with the notes succeeding them, comprise 
the information obtained regarding the wells in the crystalline rocks. 
Logs of four of these wells are shown graphically in figure 14. 



Loam and hardpan.. .. 20 

Soft rock (disinte- 
grated) 10 

Hard rock 20 

Soft, pulpy micaceous 
schist 46 



Gravel and bow] 
ders 



Micaceous rock. . . 



Gray and yellow 
schist 140 



15 Water. 


Clay 15 

Clay and small stones 
(till) 10 

Dark, gravelly Pleis- 
tocene drift 46 


r_ - _ - _" 


15 


20 
50 


o'\ • O.'. 


25 

30 Water (2 gals, 
permin.). 




Loose blocks of rock. 29 


c," - o •> o 


71 


78 Chief supply. 




96 


Soft. dry. decomposed 
rock 10 


'*■**''■ 


100 

110 Water (15 gals. 
115 permin.). 




ttk= 








4 




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13.5 


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34 

38 Small supply. 


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36 






48 Large supply; 
slightly salt. 

78 


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Gneiss 


13 

62 


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54.5 
72.5 




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hard 
25 

5 

hard 
5.5 


0; 

s / " K S* 


134.5 

159.5 
164.5 








200 Supply; very 
salt. 











2ir> 



Figure 14. — Logs of wells in crystalline rocks. 1, Well of Thomas Fogarty, Ansonia; data furnished by 
C. F. Underwood. 2, Well of Miss E. O. Wheeler, Sharon; data furnished by A. J. Corcoran. 3, Well 
of Atlantic Starch Works, Westport. 4, Well of Sidney Blumenthal Company, Shelton; data furnished 
by the company. 



78 



UNDERGROUND WATER RESOURCES OF CONNECTICUT. 





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90 UNDERGROUND WATER RESOURCES OF CONNECTICUT. 



NOTES. 

2. Penetrated 20 feet of loam and hardpan, 10 feet of soft rock, 20 feet of hard rock, 
and 46 feet of soft pulpy micaceous rock. Water was obtained in the soft micaceous 
rock. (See fig. 14.) 

7. Dug and blasted 28 feet and drilled 22J feet. Passed through 2 feet of loam, 12 
feet of till with a 1-foot layer of iron-cemented material, 14 feet of disintegrated rock, 
and 22 J feet of hard rock. 

10. Water salty on first being pumped but becomes fresh with continued pumping. 

18. In drilling, considerable amounts of water were encountered in the sand and 
gravel above the rock. This water was cased out and a small amount was found at a 
depth of 25 feet in the granite, and additional supplies, increasing in small amounts, 
were found down to a depth of 150 feet. Below this point no new supplies were 
encountered, although the total depth of the well is 315 feet. The material penetrated 
was as follows: Sand and gravel, 50 feet; granite, 100 feet; clay and gravel (probably 
disintegrated rock marking a shear zone), 20 feet; soft white micaceous rock followed 
by granite varying in hardness every few feet (probably gneiss). 

45 and 46. Maj . William Spittle has furnished the following information: One well 
was drilled to a depth of 425 feet through 12 feet of clay till and 413 feet of granitic 
rock, of nearly the same character for the entire depth, probably a gneissoid granite. 
Water first began to flow over the surface at 335 feet from the top and continued to 
increase slowly in the amount of flow and in the height of the rise above the surface 
with increasing depth. At present the water will rise at least 7 feet above the surface 
of the well in a f-inch pipe. In five months' continuous flowing the volume of water 
decreased from 4 to 3 gallons a minute. When pumped the well yielded 50 gallons a 
minute and the water level was lowered to 80 feet below the surface and remained 
steady. The second well was sunk 130 feet away and at an elevation 4 feet higher to 
a depth of 503 feet. This well yields 25 gallons a minute, but the water stands at a 
level 15 feet below the surface. The pumping of the second well did not affect the 
yield of the first. 

75. Mr. H. B. King has furnished information regarding five wells drilled for the 
Aspinook Company at Jewett City. They are from 15 to 100 feet apart and from 30 
to 60 feet in depth, all penetrating 6 to 8 feet of sand and gravel. They are located 
on a hillside at varying elevations. These wells each average 20 gallons a minute and 
are all connected to a siphon which conducts the water to the mill at an elevation about 
75 feet lower than the wells. Two of these wells, 15 feet apart, affect each other's 
yield, but the remaining wells are apparently independent of one another. 

80. A small stream of water was encountered at 83 feet from the surface, and at 180 
feet a stream of 1 gallon a minute; below this there was no increase in supply to a 
depth of 530 feet, 

82. At a depth of 32 feet this well yielded 1 gallon a minute and at 38 feet 4 gallons 
a minute. The last 10 feet of the well gave no increase of supply. 

97. Filling, 5.5 feet; silt, 5 feet; coarse gravel, 13.5 feet; coarse sand, 36 feet; hard- 
pan, 13 feet; gneiss, 62 feet; granite or hard gneiss, 25 feet; slate, 5 feet; granite or 
hard gneiss, 5.5 feet. The total depth of the well is 170.5 feet. (See fig. 14.) 

108. On the slope of a hill near the base of which are numerous springs. The water 
is siphoned from the well to tenement houses below. In dry seasons the level of water 
in the well drops 2 feet. 

132. Drilled on a small island in Long Island Sound. A trace of fresh water was 
obtained at 125 feet, hut the remaining supply was salty. 

133. Fresh water was obtained at a depth of 60 feet, evidently from gravel deposits, 
but salt water was encountered in the rock seams below this point. The well was 
plugged below 60 feet and the fresh water from the gravel is utilized. 



GROUND WATER IN CRYSTALLINE ROCKS. 91 

144. No water was found in the first 100 feet. Jn the next 70 feet a small amount 
was obtained, possibly 40 gallons a day, and the water stood at a level 107 feet below 
the surface. The well was drilled to a depth of 250 feet and an excellent supply 
obtained at 230 feet below the surface. Information furnished by II. B. King, the 
driller. 

157. The water comes from the contact of the overlying clay and the solid rock. 
No water was found in the rock, which is a quartzite schist, although 365 feet of rock 
were penetrated. 

170. The following log is furnished by the driller, A.J. Corcoran: Solid clay, 15 feet; 
clay and small stones (till), 10 feet; dark gravelly material, 46 feet; loose blocks of 
rock, 29 feet; soft and dry decomposed rock, JO feet; hard rock, 5 feet. A small 
yield of water, 2 gallons a minute, was found at a depth of 30 feet, but no more was 
encountered until the last 5 feet of hard rock was penetrated, when a supply of 15 
gallons a minute was obtained. (See fig. 14.) 

176. Water was found in the superficial drift, but was lost on encountering a dry 
seam in the rock. 

202. A good supply of water was obtained at a depth of 25 feet, but this flowed off 
at 45 feet, and when water was struck again at 60 feet it rose to this point and flowed 
off in the open rock seam. 

223. At 35 feet the well pumped 100 gallons an hour and the water rose within 16 
feet of the surface. A second and very large supply was encountered at a depth of 
51 feet and the level of the water dropped to 25 feet below the surface. 

227. Penetrated 34 feet of gravel and bowlders and 41 feet of micaceous rock, in 
which a little fresh water was found at 38 feet below the surface and a large flow of 
slightly salt water at 48 feet below the surface. The rest of the well was through a 
rock described as gray and yellow sandstone (probably schist). At 200 feet very salt 
water was encountered, but this is held back by a plug. (See fig. 14.) 

PRACTICAL APPLICATIONS. 

PERCENTAGE OF FAILURE OF WELLS. 

Wells in crystalline rocks are unlike most other wells, in that it is 
impossible to predict their success or failure, even when numerous 
wells have been sunk previously in the same locality. For this reason 
a well driller will rarely guarantee to obtain water from such a well, 
although occasionally water is guaranteed and an additional price 
per foot charged to offset the driller's risk of failure. 

When a well is considered a failure the fault lies either with the 
quality or with the quantity of the water obtained. It is a very 
exceptional well in which no water supply is obtained in the rock. 
Nearly all wells encounter some water in the surface material above 
the rock, but it is common for the drill to penetrate 30 or 40 feet of 
rock, and occasionally even 100 feet, without obtaining enough water 
in the rock to keep the drillings wet, so that water must be poured 
in at the top to allow the drilling to continue. Although no satis- 
factory data are at hand regarding the number of wells which have 
failed to obtain any water, it is certain that the number is very 
small. Among 237 wells only 3, or 1.25 per cent, are recorded as 
obtaining no water. Drillers are naturally averse to giving infor- 



92 UNDERGROUND WATER RESOURCES OF CONNECTICUT. 

mation regarding unsuccessful wells which they have sunk, but the 
available information indicates that, though dry wells are uncommon, 
there are a considerable number of wells in which the yield of water 
has been less than 2 gallons a minute. For certain purposes, such as 
manufacturing, this small supply would be considered a failure, but 
for domestic use where the water is obtained by a hand pump or 
windmill a supply of this amount is generally sufficient. Among 134 
wells whose yield is known, only 17, about 12.5 per cent, furnish less 
than 2 gallons a minute. It is probably a conservative estimate to 
state that not less than 90 per cent of the wells sunk in the crystal- 
line rocks have given supplies of sufficient amount for the use required. 

The greater number of unsuccessful wells in regard to quality are 
located along the coast or on tidal rivers, where the well supplies are 
affected by sea water. When a well is within a few hundred feet of 
salt sea water, it sometimes happens that salty or brackish water is 
obtained, although perfectly fresh water is yielded by other wells in 
similar locations. Six wells are recorded in which the water has been 
contaminated in this way and others, regarding which definite infor- 
mation is lacking, are known to have been failures for the same 
reason. It is certain that a large percentage of wells near salt water 
have yielded brackish water and any well sunk in rock on a small 
island or within 500 feet of the sea is likely to afford an unsatis- 
factory supply. As nearly as can be estimated from present infor- 
mation, the chances of failure for such wells are between one in four 
and one in three. 

When there is a choice of several locations, the well should be as 
far as possible from the sea and at as high elevation as convenient. 
Several wells that have been ruined by the entrance of salt water 
are situated on old salt marshes or on filled ground that is but 
slightly elevated above tide level. In the quarry at Millstone Point, 
near New London, which is about 150 feet from the sea, brackish 
water enters through the horizontal seams in the upper part of the 
quarry wall nearest the Sound. The rock outcrops in the sea and 
the open seams have abundant opportunity to absorb salt water. 

VARIATIONS IN YIELD AND DEPTH. 

The depths and yields of wells vary widely within very small 
areas. When considered collectively, as in the table on page 102, it 
is seen that there is an average increase in the amount of water 
obtained with increase in depth of the wells. It is often found, how- 
ever, that of two wells sunk within 100 feet of each other in the same 
kind of rock, one will obtain a plentiful supply of water while the 
other may be sunk to twice the depth and obtain only one-tenth the 
amount. This is a typical case which nearly every Connecticut well 



GROUND WATER IN CRYSTALLINE ROCKS. 93 

driller will present in one form or another when information regard- 
ing his drilling experiences is requested. 

This variation within short distances is due to the varied occur- 
rence of the water-bearing fractures considered on the previous pages. 
One well may be sunk in a portion of the rock in which the fractures 
are numerous and closely spaced or it may intersect a large open 
fracture; the second well, only 100 feet away, may be located in an 
area of widely spread fractures or it may intersect only fractures 
with closely compressed walls and consequently can obtain only a 
meager water supply. Owing to the general steep pitch of joint 
planes, there would be little chance of two wells intersecting the 
same fracture, although they might possibly intersect connecting 
fractures and in this way affect each other's yield. Even where two 
wells intersect connecting fractures at the same depth, the yield of 
the two wells would probably be different, owing to differences in the 
opening of the fractures. 

LIMIT OF DEPTH FOR WELLS IN CRYSTALLINE ROCKS. 

Although the well records given on pages 78-89 show that supplies 
of water have been obtained at all depths from 15 feet to 800 feet, the 
largest percentage of failures is among the wells more than 400 feet 
in depth. The reasons for the increasing probability of failure with 
increasing depth are indicated in the discussion of joints (pp. 61-64), 
where it is shown that increased depth means a decrease in number 
and a tightening of joints. Increased depth usually means an 
increase in the cost per foot, as drilling is necessarily slower and con- 
sequently more expensive at considerable depths. Owing to the 
great length of rope and the necessity of waiting for the recoil of the 
stretched rope fewer blows can be struck per minute and there is 
also greater danger of losing the drilling tools. 

In view of the increasing cost and the decreasing probability of 
finding water-bearing seams with increasing depth, and of the great 
variation in water-bearing fractures within very short distances, it 
seems manifest that if a well is unsuccessful within a certain depth 
the best policy is to abandon the well and start a new one at some 
distance from the first. In one place a well was abandoned in this 
manner and a second and successful one sunk by simply turning the 
rig around and drilling a hole less than 20 feet away. It is always 
preferable, however, to move as far away from the first well as 
possible. 

In deciding at what depth an unsuccessful well should be aban- 
doned a number of factors must be taken into consideration, but an 
estimate that will prove of value may be made from the available 
well records. The table on page 100 shows that the average depth 



94 UNDERGROUND WATER RESOURCES OF CONNECTICUT. 

of the wells varies considerably for different rocks. The average 
depth in rock of 163 wells is 88.8 feet and the average total depth, 
including the surface material overlying the rock, is 108.4 feet. 
About 90 per cent of the wells are under 300 feet in depth and 82 
per cent under 200 feet. In many of the wells which have gone 
below 250 feet the main supply and in several the entire supply has 
come from seams less than 250 feet in depth. From a study of the 
recorded wells it would appear, therefore, that if a well has pene- 
trated 250 feet of rock without success the best policy is to abandon 
it and sink in another location. For wells in granodiorite, which 
have been successful at an average greater depth than in other rocks, 
this depth might be somewhat too small, but for wells in other rocks 
it is possible that a maximum depth of 200 feet should be adopted. 
The wells that penetrate 200 feet or less of rock show a rather 
regular increase in yield of water with increasing depth, but in deeper 
wells than this the tendency is toward a smaller average yield owing 
to the failure of many of the wells. The average yield of 123 wells 
in the crystalline rocks is 12.7 gallons a minute, and as their average 
depth is 108 feet the cost of the average well for this yield of water 
at $4.25 a foot is $459. 

QUALITY OF WATER. 

A general discussion of the chemical composition of well waters 
and a number of analyses of well waters derived from crystalline 
rocks may be found on pages 166-168, 176-179. The general quality 
of water from these rocks is excellent and they are well adapted to 
boiler use. 

TEMPERATURE OF WATER. 

The temperature of the water is entirely dependent on the depth 
from which it comes. In wells less than 50 feet deep the water will 
show variations in temperature agreeing in a modified form with the 
seasonal changes. In wells more than 50 feet in depth the tempera- 
ture of the water increases at the rate of about 1° to every 60 feet 
of depth. The average temperature of the water of 49 wells in the 
crystalline rocks is 50.5° F. The average annual temperature of Con- 
necticut is 47° F. 

LOCATION OF WELLS. 

So many factors are involved in considering the location of a well 
that it is impossible to lay down any set rule for choosing a location. 
Before sinking a well it is always advisable to find out what wells 
have been sunk in the vicinity and what success they have had. 
The list of well records on pages 78-89 gives all the information at 
hand, although there are probably as many more wells in Connecti- 
cut regarding which no information has been obtained. 



GROUND WATER IN CRYSTALLINE ROCKS. 95 

In localities where, owing to limited space or other factors, there is 
only one place where a well can be sunk, the only questions to be 
considered are the possibility of obtaining a satisfactory supply and 
the probable cost. For such wells the information embodied in this 
report should be of considerable value. 

Where there is a choice of situations for the well the following 
points should be considered. The well should be as far removed 
from contaminating influences as possible. This is particularly 
important for wells near sea water. (See p. 174.) It is better to sink 
the well where there is a heavy covering of surface material rather 
than on a bare rock ledge. If there are rock exposures near by, a 
study of the joints may be of assistance in locating the well so as to 
intersect possible water-bearing fractures. 

The Aspinook Company, at Jewett City, has adopted a very suc- 
cessful scheme which doubtless could be used in many other places. 
The mill is located below a hill and a series of wells were sunk on the 
hillside at a considerable elevation above the mill. The water is 
obtained by means of a siphon and a very considerable pumping 
expense is thus saved. The same method has been adopted for indi- 
vidual wells elsewhere and has proved satisfactory. 

In order that a siphon may be used, the water level must be not 
more than 30 feet from the surface and the lower end of the siphon 
pipe or the escape valve must be at an elevation lower than the 
water level. The average depth from the surface of the ground to 
the water level in the recorded wells is 19 feet on hills and 15 feet on 
slopes. The water level will of course lower to some extent when 
water is drawn out and the degree of lowering will be proportional 
to the volume of water removed, but in many wells the lowering will 
not be sufficient to affect the use of the siphon. The greatest cer- 
tainty of success will be on hillsides where there is a covering of clay 
or hardpan and where there are no outcrops of rock showing above 
the surface at elevations lower than the top of the well. 

The wells located on hills average less in cost than those in valleys, 
owing to the greater depth of the valley wells, as shown in the table 
on page 102; but the average yield of wells on hills and in valleys is 
nearly the same. 

CONSTANCY OF YIELD. 

The wells appear to maintain a remarkably constant yield from 
year to year. Although the drilling of wells in the crystalline rocks 
is a comparatively new venture and almost all of these wells have 
been sunk in the last three years, no well in which water was obtained 
has failed to yield a supply on continued use. In very shallow wells 
dry seasons have marked some decrease in supply, but the decrease 
has been small and only temporary. In a number of wells the sup- 



96 UNDERGROUND WATER RESOURCES OF CONNECTICUT. 

ply has increased after continued pumping, probably owing to the 
removal of material lodged in the rock crevices, which are cleaned 
out by the running water. 

In some wells supplies obtained at short distances below the surface 
have been lost with deeper sinking, an open dry crevice struck at a lower 
level allowing the water to run off. Such occurrences are unusual 
and are found at relatively shallow depths. During the drilling of 
any well it is usual to find a number of fractures supplying water. 
Often the water derived from small sources will stand at a certain 
level in the well and when the main supply is struck will rise or fall, 
depending on the height at which the water stands in the main 
crevice. There will of course be an equalizing between the various 
supplying fractures. If the well penetrates one saturated fracture 
in which the water stands at 10 feet below the top of the well and a 
second fracture in which the water stands at 30 feet below the top, 
the water level in the well will occupy an intermediate point some- 
where between 10 and 30 feet below the surface. 

FLOWING WELLS. 

The question is often asked regarding the possibility of obtaining 
flowing wells in Connecticut. A number of flowing wells have been 
obtained in the sandstone area in the central and northern portions 
of the State, but a flowing well in crystalline rocks is a very unusual 
occurrence. Information has been obtained regarding six wells in 
the Connecticut crystalline areas in which the water has maintained 
a constant flow over the top for some time and several wells are 
known in which the water has flowed over the surface for a few 
minutes but has eventually lowered to a level below the mouth of the 
well. 

The occurrence of flowing wells is therefore common enough to 
demand an explanation. Four of these wells have been personally 
visited and the position of the others is known approximately. Each 
of the wells is located on the side slope of a hill or in a small valley 
where there is a considerable elevation back of the well. One well 
at Greenwich is on a very gently sloping surface so that it appears to 
be at the top of the hill, but in reality the ground rises gradually to 
an elevation at least 40 feet higher than the well. All the wells are 
in markedly glaciated areas, where there is a considerable thickness 
of clay till overlying the rock, and there are no neighboring rock 
outcrops except at one flowing well called the Buttress Dyke Spring, 
near New Haven. This well is in an area of schistose rock where the 
hill back of the well exhibits numerous outcrops, but there are no 
rock ledges showing at elevations lower than the well. 

From the study of the individual wells and of the general occurrence 
of water in rock fractures, it is concluded that the artesian conditions 



U. S. GEOLOGICAL SURVEY 



WATER-SUPPLY PAPER 232 PLATE III 




A. FLOWING WELL AT NOROTON HEIGHTS. 




B. WEATHERING DUE TO GROUND WATER IN GRANITE QUARRY. 



GROUND WATER IN CRYSTALLINE ROCKS. 97 

giving rise to flowing wells in Connecticut are due solely to the capping 
of clay till above the rock and that this capping is sufficiently imper- 
vious to prevent the water escaping from the rock crevices, at least 
with sufficient freedom to destroy the artesian head. The water 
occupying the rock seams is under hydrostatic pressure owing to its 
confinement on the sloping hillside, and, an easy escape being offered 
by the open well, the water rises to the surface. It is probable that 
the joints that give rise to the flowing wells are more nearly at right 
angles to the slope of the hillside than parallel to it. The same con- 
ditions might arise where the joints have a pitch parallel to the 
surface slope and a very low inclination, but the pitch of most of the 
joints is so steep that they would intersect the surface so near the 
well as to give little or no head to the water. 

As far as water supply is concerned, flowing wells need not be con- 
sidered as of any particular importance in Connecticut. In the first 
place it is impossible to predict that a well will flow, even though 
the most favorable location be chosen. At Noroton Heights two 
wells were sunk within 150 feet of each other in the same kind of 
location, one of which flowed 7 feet above the surface, while in the 
other the water rose only within 15 feet of the top. Second, the flow 
at each of the flowing wells has been small, from 1 to 4 gallons a 
minute. This supply is too small for the use made of it at most of 
the wells and pumping machinery has been installed. The wells 
have yielded unusually large supplies when pumped, but the level of 
the water has sunk to a considerable distance below the surface. 
It is not known whether the wells would again flow if pumping were 
stopped. (See PL III, A.) 

It is probable that in the wells which flowed for only a few minutes 
after being struck the water then found an escape through open dry 
fractures in the upper portion of the well, as the water level dropped 
to several feet below the surface. 

WELLS IN VARYING ROCK TYPES. 

A study of joints and other rock fractures indicates that these 
structures vary with varying rock types, and as the water supply of 
wells is directly dependent on the fractures it is to be expected that 
there will be corresponding variations of supply in the wells in the 
different rock varieties. These variations are discussed below. The 
records on which the discussion is based are not as complete as might 
be desired, but are sufficiently numerous to have considerable weight. 

Wells in granite. — It has been shown that the fractures particu- 
larly characteristic of granite masses are the nearly horizontal joints 
which in general run parallel to the surface of the ground. These 
joints are manifestly of considerable importance in the transmission 
and storage of water, but it is doubtful whether they are sources of 
463— irr 232—09 7 



98 UNDERGROUND WATER RESOURCES OF CONNECTICUT. 

large supply to wells. In granite quarries where the horizontal 
joints are well developed, the greater portion of the water entering 
the quarry comes through these flat joints. Owing to their parallel- 
ism to the surface these joints are not in a suitable position to receive 
water from the material overlying the rock, and must get their main 
supply of water from that descending through the vertical joints. 
In the quarry walls the largest amount of water escapes and the 
heaviest decomposition of the rock occurs near the major vertical 
joints, indicating that the vicinity of such joints is the place of greatest 
water circulation. 

As a well sunk in granite must pass through a large number of 
horizontal seams, which are far more abundant in the upper 50 feet 
of rock than in the next 50 feet, it would appear that if these seams 
were saturated and could yield good water supplies the granite wells 
should furnish unusually large supplies at comparatively shallow 
depths. 

The records show, however, that the wells in granite yield about 
the same as those in gneiss and schist, and that although their average 
depth is 10 per cent less than that of the wells in gneiss it is slightly 
greater than the average of the schist wells. The natural inference 
to be drawn is that though the number of contributing fractures to 
any one well is much greater in granite than in the other two main 
rock types, the total yield of the well is no greater than the amount 
furnished by the vertical joints to the horizontal joints. 

In granite the vertical joints are more irregular and probably more 
widely spaced than in the other rock types, but they are well connected 
with one another by the intersecting horizontal joints. The con- 
tributing area to a granite well should occupy a space with an ap- 
proximately uniform radius around the well. 

Wells in schist and gneiss. — Little difference can be distinguished 
between the occurrence of joints in schist and that in gneiss, and in 
fact the two rocks grade into each other so completely that it is in 
some places difficult to say whether a rock is a schist or a gneiss. 

The marked development of horizontal joints characteristic of 
granite is lacking in these rocks, and the more regular character of the 
vertical joints tends to produce a different manner of circulation 
through the rock. A single well, instead of drawing water from an 
area surrounding it on all sides, will draw from long distances through 
the feeding fractures and the vertical fractures connecting with 
them. 

The wells in schist and gneiss have nearly the same average yield, 
but those in gneiss average 15 per cent deeper than those in schist. 
It is possible that the supply for the wells in schist comes not only 
through the joints but also through fissility openings or small frac- 
tures parallel to the schistosity. Such fractures are common near 



GROUND WATER IN CRYSTALLINE ROCKS. 99 

the surface, and owing to their inclination might well absorb consider- 
able volumes of water. Because of the small size and lack of con- 
tinuity of these openings they would yield water very slowly to the 
well, but might give an important amount in the aggregate. The 
derivation of a supply through such openings, which would have their 
greatest development near the surface, would account for the relative 
shallowness of wells in schist. 

That fractures parallel to the schistosity may be important car- 
riers of water is well shown on the east bank of Connecticut River 
above Hadlyme Landing, where there is a long exposure of fissile 
schist and a number of small springs issue from partings parallel to 
the schistosity. 

Wells in quartzite schist. — In the northeastern portion of the State 
there is an important development of a rock which is a schist but 
is unlike most of the schists of Connecticut and will be treated 
separately. This rock is an altered quartzite and consists very largely 
of quartz grains with a very small percentage of other minerals. No 
study was made of the fractures in this rock, but information has 
been obtained regarding five wells which were drilled in it, three of 
which are more than 300 feet in depth and one more than 200 feet. 
In each one the supply has been very small and unsatisfactory. 
Though the number of these wells is small, the evidence indicates that 
the rock is a very unreliable source of water supply and that the 
fractures are few or poorly developed. 

Wells in pJiijlliie. — Near Woodbridge and at Woodmont several 
wells have been drilled in a greenish slaty rock or phyllite in which 
the supplies have proved very unsatisfactory. The cleavage of the 
rock is nearly vertical, causing difficulty in drilling, and most of the 
fractures appear to be filled by some cementing mineral matter. 
The wells that have been drilled in this rock are comparatively shal- 
low, but the water obtained has been so universally poor that the 
probability of getting a satisfactory supply appears to be very slight. 

Wells in limestone. — Comparatively few wells have been drilled in 
the limestone area in the western part of the State, where springs are 
so numerous as to constitute far the most important source of water 
supply. The limestone itself is largely recrystallized and changed to 
a marble. It is dolomitic in part, but unlike many dolomites is com- 
pact and contains very little pore space. 

The fracturing is very thorough and in fact so complete that it has 
been found impossible to obtain blocks for building purposes large 
enough to warrant quarrying. The limestone is traversed through- 
out by irregular fractures which divide it into a series of comparatively 
small blocks. Solution is very effective in limestone, as the calcium 
carbonate constituting the bulk of the rock is readily soluble in 
water containing carbon dioxide. No large solution caverns, such as 



100 



UNDERGROUND WATER RESOURCES OF CONNECTICUT. 



are typical of many limestones, have been found in the Connecticut 
limestones, but the fractures generally have decomposed borders 
several inches wide and are sufficiently enlarged to offer easy passage 
to water. 

Wells should be very successful in this rock, but because of its 
highly fractured condition water passes through it rapidly and the 
level of the water in the wells will probably be at a greater distance 
below the surface than in rocks of other types. 

Wells in granodiorite. — In the vicinity of Stamford and Greenwich 
the wells drilled in schistose granodiorite have met with a consider- 
able degree of success. The rock outcrops in this area show a well- 
developed and rather closely spaced jointing which is nearly at right 
angles to the schistose structure of the rock. There is no apparent 
reason why the wells in this rock should differ from those in schist 
and gneiss, but the average depth and average yield are much greater. 
It is possible that especially large supplies have been required in this 
locality and that for this reason the smaller supplies in the upper 
portion of the rock have been insufficient and the wells have been 
drilled until a large supply was struck. 

STATISTICAL TABLES. 

Table 1.— Yields of water at varying depths in the rock below the covering of surface 

material. 



[" Vol. "= average yield in gallons per minute; "No."=number of records from which the average is taken.] 





0-30 


30-50 


50-70 


70-90 


90-110 
















Vol. 


No. 


Vol. 


No. 


Vol. 


No. 


Vol. 


No. 


Vol. 


No. 


Schist . 


3.2 

7 
1 


2 
1 

1 






9.5 
9.8 
12.4 


4 
5 

14 


21.6 

20.5 

7.6 

8.0 

6.0 


3 

2 

7 

..... 


22.1 
14.4 

5.5 




6 


G ranite 


6.7 
11.9 


9 
13 


8 




2 


Granodiorite 


1 


Quartzite schist 


































Average 


3.6 


4 


9.75 


22 


11.3 


23 


12.4 


14 


15.2 


17 









110-200 


200-300 


300-400 


400-500 


500-650 
















Vol. 


No. 


Vol. 


No. 


Vol. 


No. 


Vol. 


No. 


Vol. 


No. 




8.5 
13 

8.3 
46.0 


2 
5 
8 
6 











50 


1 
1 








16 

33.0 
10.7 



3 

2 
3 
1 




22.0 

2 

2 


1 
2 

1 
1 








14.0 


2 


Granodiorite 














7 


2 














Average 


20.2 


21 


16.7 


9 


11.5 


4 


26.0 


5 


5.2 


4 







Note. — The information at hand shows no relation between the depth of the surface drift and the yield 
or success of wells. 



GROUND WATER IN CRYSTALLINE ROCKS. 101 

Table 2. — Yield of wells more than 400 feet deep, with reference to topographic position. 



Location. 




Yield (gal- 
lons per 

minute). 



Valleys 

Hills... 

Slopes.. 
Island.. 



25 

a 10 

26 

50 

40 

Poor. 

2 

Dry. 

12 

4 

*>3 



a All water obtained at 120 feet. & Salty. 

Table 3. — Average yield of wells in various locations. 



Location. 



Average 
yield (gal- 
lons per 
minute. 




Number of 
records. 



Valleys 
Hills!.. 
Slopes.. 
Plains.. 



Table 4. — Relation of average yield of wells in various topographic locations to average 
yield of wells in any rock type and in any location. 

[Yield in gallons per minute.] 



Rock. 



Location. 



Relation of average yield of 
wells in any location to 
average yield of all wells in 
same kind of rock. 



Average 


Average 


yield for 


yield for 


location. 


rock type. 


9.3 


17.4 


10.3 


17.4 


21.7 


17.4 


26.5 


17.0 


4.7 


17.0 


10.0 


17.0 


21.8 


17.0 


10.1 


17.0 


24.3 


17.0 


24.7 


26.4 


2.2 


26.4 


42.5 


26.4 



Differ- 
ence. 



Relation of average yield of 
wells in any location to 
average yield of all wells in 
same kind of location. 





Average 


Average 


yield for 


yield for 


all in 


location. 


similar 




location. 


9.3 


20.6 


10.3 


8.7 


21.7 


24.4 


26.5 


20.6 


4.7 


8.7 


10 


24.4 


21.8 


20.6 


10.1 


8.7 


24.3 


24.4 


21.7 


20.6 


2.2 


8.7 


42.5 


24.4 



Differ- 
ence. 



Granite . 



Schist. 



Gneiss. 



Other crystalline rocks. 



Hills... 

Slopes . 

Valleys 
[Hills... 
^Slopes. 
(Valleys 

Hills... 
{Slopes. 
IValleys 
(Hills... 
{Slopes. 
[Valleys 



-8.1 

- 7.1 
+ 4.3 
+ 9.5 
-12.3 

- 7 
+ 4.8 
-6.9 
+ 7.3 
-11.7 
-24.2 
+ 16.1 



-11.3 
+ 1.6 
-2.7 
+ 5.9 

- 4 
-14.4 
+ 1.2 
+ 1.4 

- .1 
+ 1.1 

- 6.5 
+ 18.1 



102 



UNDERGROUND WATER RESOURCES OP CONNECTICUT. 



Table 5. — Relation of level at which water stands in wells in various locations to surface 
of rock which marks bottom of overlying drift. 



Rock. 



Granite . 



Schist. 



Gneiss. 



Granodiorite 



Location. 



Hills... 
Valleys 
Slopes.. 
Plains.. 
Hills... 
Valleys 
Slopes. 
Hills... 
Valleys 
Slopes., 
Plains.. 
Hills... 
Valleys 
Slopes.. 
Plains.. 



Percentage of 

wells in which 

water level is 

below rock 

surface. 



37 
11 
41 
50 
62.5 


50 
69 
22 
44 


71 


60 
33 



Percentage of 

wells in which 

water level is 

above rock 

surface. 



50 

89 

50 

50 

37.5 
100 

33 

21 

78 

36 

50 



100 

40 

67 



Percentage of 
wells in which 

water level is 

even with rock 

surface. 



Note. — A summary of the results for all wells may be found on page 133. 

Table 6. — Average depth and yield of wells in varying rock types. 





Depth of surface 
material. 


Depth in rock. 


Total depth. 


ield. 


Rock. 


Feet. 


Number 

of 
records. 


Feet. 


Number 

of 
records. 


Feet. 


Number 

of 
records. 


Gallons 

per 
minute. 


Number 

of 
records. 


Granite 


20.6 
16.3 

13.7 
24.1 
32.5 

14.4 


45 
69 

23 
15 
3 
5 


100.5 
112.6 

96.0 
138.5 
411. 

80.2 


45 
70 

23 
15 
3 
5 


122.5 
131.4 

109.7 
156.6 
443.5 
93.8 


54 
73 

23 
19 
3 

5 


13.0 
12.3 

13.9 
33.0 
7.25 
Very poor. 


35 




50 


Schist (other than quartz- 


16 




13 


Quartzite schist 


3 


Phyllite (slate) 


5 







Table 7. — Average depth from surface to water level in the well. 



Location. 




Number of 
records. 



Hills... 

Valleys 
Slopes.. 
Plains.. 



Table 8. — Average depths, in feet, of surf ace material, of rock, and of the entire well for 
the records at hand, exclusive of wells more than 400 feet in depth and of wells known 
to be dry. 



Location. 



Average 

depth of 

surface 

material. 



Average 

depth in 

rock. 



Average 
total depth. 



Number 
of records. <* 



Valleys 
Hills... 
Slopes.. 
Plains.. 



104.5 
94.0 
79.4 
74.0 



140.5 
111.0 
100.4 
84.0 



a Average depth of surface material based on only 122 records. 
Note.— Average total depth of all these wells is 108.4 feet. 



GROUND WATER IN CRYSTALLINE ROCKS. 103 

It is clearly shown in Table 1 that there is an increase in the 
average yield of wells with increase in depth to a certain point, beyond 
which the average yield tends to decrease, owing mainly to the larger 
proportionate number of the deep wells that prove to be failures. 
The table also indicates that most of the wells are between 30 and 
200 feet in depth. The wells in granite are evenly distributed over a 
considerable range in depth, but most of the wells in gneiss are 
shallow, 70 per cent being less than 100 feet deep. The wells in 
granodiorite whose records are available are mostly in the schistose 
area near Stamford, and the data indicate that in this rock good sup- 
plies of water are obtained at considerable depth. 

Table 8 indicates that the impression of well drillers that wells 
obtain water at shallower depths on hills than in valleys is borne out 
by the facts, but that the greater part of the difference is due to the 
heavier deposits of surficial drift in the valleys. On the other hand, 
it is shown in Table 3 that the average yield of wells in valleys is 
somewhat greater than that of wells on hills. If there were any 
relation between the yield of wells and their topographic situation it 
would seem that wells located on slopes should give an average yield 
intermediate between that of the wells on hills and that of the wells 
in valleys. On the contrary, the wells on slopes average a yield less 
than half of that for either of the other locations and the wells on 
slopes are also the shallowest of the three groups. 

Table 5 shows that the ground water in wells in granite has an 
occurrence differing from that in the other rock types, the position of 
the water level with reference to the rock surface being the reverse in 
wells on hills and slopes to that in the other rocks, though in the 
wells in valleys the same relation is shown by all rock types., 



CHAPTER V. 

GROUND WATER IN TRIASSIC SANDSTONES AND TRAPS. 

INTRODUCTION. 

The bed rock of Connecticut, as is shown on the map (fig. 11), 
consists of two main types, widely separated in character and age — 
the pre-Triassic metamorphic crystalline rock and the Triassic sand- 
stone, conglomerate, shale, and lava. In the sedimentary rocks and 
traps of the Triassic area the water occurs in four situations — within 
the rocks themselves, in bedding planes, in joints, and along fault 
lines. 

WATER WITHIN THE ROCKS. 

CONDITIONS OF OCCURRENCE. 

No rock is so dense as to exclude water entirely. However firm 
and compact it may appear to be, there are spaces between the indi- 
vidual grains and crystals, of capillary size and larger, which, though 
invisible, allow access and movement of water. Though it is true 
that all rocks possess a capacity to hold water, yet the amount of 
available space varies within wide limits, in accordance with the 
character of the rock. In the crystalline rocks, composed of closely 
interlocking crystals, there is small space for water, and the densest 
known granite (from Montello, Wis.) has an average porosity of only 
0.237 per cent, or about 1 part in 400. In sand the pores may con- 
stitute 30 to 40 per cent of the volume; in sandstone, 20 per cent or 
more. The sedimentary formations of Triassic age in Connecticut 
include sandstone, conglomerate, and shale, all of which have rela- 
tively large water capacity. 

WATER IN SANDSTONE. 

The prevailing sedimentary rock in Connecticut is sandstone, 
which varies in texture from coarse to fine and in color from choco- 
late brown to reddish brown, with local green and buff tints. Com- 
mercially the rock is known as " brownstone," and the quarries of 
Portland, Long Meadow, and other places have furnished a great 
amount of it for building purposes. The large outcrops of sandstone 
in Connecticut are generally not homogeneous, presenting as a rule 
wide variation in grain, conformity, order of stratification, and rela- 
tive amounts of the component strata. Overlapping lenses of sand- 
]04 



GROUND WATER IN TRTASSIC SANDSTONES AND TRAPS. 



105 



stone. 



conglomerate, 



and shale, rather than uniform beds of sand- 
stone, make up the formation. In one of the quarry pits at Port- 
land four types of rock are sufficiently distinct to be separated for 
commercial purposes. 

The Triassic sandstone of Connecticut consists of quartz, feldspar 
(in many localities kaolinized), biotite, muscovite, and garnet, with 
fragments of chlorite schist, mica schist, gneiss, and granite. The 
cement which holds the grains together and gives color to the rock is 
partly a film of iron oxide surrounding the grains and partly fine clay. 

Sandstone in general has great water-holding capacity, and the 
Connecticut varieties form no exception. A sample from the Port- 
land quarry which was dried carefully and then immersed in water 
for three months was found to have increased in weight during that 
time from 150 to 154 pounds, an absorptive ratio of about one- 
fortieth of the weight of the specimen examined. The amount of 
water absorbed was about 2 quarts for every cubic foot, equivalent 
to 88,502,857 barrels for a square mile of rock 200 feet deep. This 
is sufficient water to form a lake 1 mile in diameter and 50 feet deep. 

In spite of its capacity for holding such enormous quantities of 
water, the exposed portions of the sandstone usually appear dry. 
In railroad cuts and on cliffs 
the water is not seen to ooze 
out of the rock nor to form a 
film over its surface. It is 
only in artificial openings, such 
as wells, that the water drips 
from the rock itself. This ab- 
sence of water on the face 
of a natural rock outcrop does 
not indicate that the rock is 
not saturated at a short dis- 
tance back of the face, for the 

water within the rock would naturally seek a lower level of escape 
through some bedding plane or fracture nearer the base of the 
hill. In several localities springs issue from crevices immediately 
above which the rock is practically dry. In such localities the 
water table is depressed at the point of leakage. 6 (See fig. 15.) The 
depth to which saturated sandstone extends varies with the topo- 
graphic location and character of the rock, but is in few places more 
than a few hundred feet. Wells are reported where the rock was so 
dry between depths of 200 and 300 feet that water had to be pumped 
into the hole to enable the drill to perform its work. 




IMPERVIOUS BED 



Figure 15.— Diagram illustrating depression of water 
surface at point of leakage in sandstone. 



a Stone, vol. 9, 1894, p. 20. 

b Fuller, M. L., Water-Supply Paper U. I 



Geol. Survey No. 110, 1905, p. 98. 



106 UNDERGROUND WATER RESOURCES OF CONNECTICUT. 

WATER IN CONGLOMERATE. 

Interbedded with the sandstones are lenses and short layers of 
conglomerate, and at several localities, as in the vicinity of New 
Haven and elsewhere along the Triassic border, this rock occurs in 
great abundance. The pebbles in the conglomerate average from 
1 to 5 inches in diameter, but reach extremes of more than 2 feet. 
Conglomerate is cemented gravel, and the pebbles of which the Triassic 
conglomerate of Connecticut is composed are crystals of quartz, 
feldspar, and mica, together with partly rounded fragments of schist, 
gneiss, porphyries, granite, and pegmatite. The pebbles, large and 
small, lie in a matrix of sandstone. The cementing material and 
coloring matter are identical with those of the sandstones, except 
that there is perhaps a smaller amount of clay. 

The conglomerate contains within itself abundant water, as its pore 
space is relatively large, but, like the sandstone, it seems to give up 
its water readily to joints and other large openings and to be rela- 
tively dry at great depths. The deep wells in the Connecticut 
Triassic area which have been failures — the Northampton well, 3,700 
feet deep; the Westfield well, 1,100 feet; the Forestville well, 1,290 
feet; and the Winchester Arms Company well at New Haven, 4,000 
feet — are in the conglomerate. The easterly dip of the conglomerate 
along the west side of the Triassic area suggests conditions favorable 
for flowing wells, especially as the upturned edges of the strata are in 
a position to receive the water from the Western Highlands and to 
carry it eastward into the ground. These favorable conditions are, 
however, offset by the lack of continuity in the rock strata due to 
the presence of joints and faults. (See pp. 133-135.) 

WATER IN SHALES. 

The shales of the Connecticut Valley, popularly called "slate," do 
not cover wide areas to the exclusion of other rocks, but occur as 
beds or lentils interstra tiffed with the sandstones, conglomerates, and 
lavas which make up the Triassic of the State. Typical shales are 
layers of mud that have become consolidated by the addition of 
cementing material and by the pressure of overlying rock masses. 
The fragments of which they are composed are largely grains of 
quartz, feldspar, and mica, either fresh or partly disintegrated, and 
the layers into which a shale outcrop is divided are usually but a 
fraction of an inch thick. 

Pure mud shales contain a large amount of water, but the pore 
spaces are so small that they retain it with great tenacity and wells 
sunk in unbroken shale beds of homogeneous structure remain as 
holes with moistened sides but with an amount of water insufficient 
for practical purposes. The Triassic shales, however, are not homo- 



U. S. GEOLOGICAL SURVEY 



WATER-SUPPLY PAPER 232 PLATE IV 




A. VERTICAL AND HORIZONTAL JOINTS IN SANDSTONE. 




B. VERTICAL AND HORIZONTAL JOINTS IN TRAP. 



GROUND WATER TN TRIASSIC SANDSTONES AND THAI'S. 107 

geneous layers of compressed mud and silt, but thin beds of shale 
alternating with sandstone, and much rock which passes for shale 
or "slate" is in reality a very fine grained sandstone of large water 
capacity. Furthermore, the shale contains some small lenses of lime 
and gypsum, possibly also salt, which are readily dissolved and leave 
channels and pipes through which ground water may circulate with 
great freedom. The shales are furthermore broken by joints and 
faults of sufficient extent to permit the passage of water. These 
characteristics make the Triassic shales of scarcely less value than 
the sandstone as sources of water, although the quality of the water 
is usually inferior. The chief importance of clay shales, however, is 
not as a water carrier, but as a confining layer in the midst of more 
porous material which serves to collect and transmit the water, giv- 
ing rise to springs and determining favorable locations for wells. 
(See p. 109.) 

WATER IN TRAP. 

There are two chief types of trap rocks in the Connecticut Valley — 
extrusive volcanic rocks (basalt) and intrusive rocks (diabase) — but 
considered in regard to their water-bearing capacity they may be 
treated as one. Except for the amygdaloid cavities in the lavas, 
filled with fresh or decomposed calcite, zeolites, etc., the traps are 
exceedingly dense, and the interlocked crystals of feldspar and py- 
roxene afford practically no access to surface waters. That ground 
water does not penetrate these rocks is clearly shown by the presence 
of unaltered anhydrite and bitumen at depths less than 30 feet from 
the surface. Moreover, the topographic form of the trap ridges pre- 
vents their absorption of surface waters. They project high above 
the surrounding plain and slope in two directions, and the rain that 
falls on them is hurried to the lowlands in streams. In fact, the lower 
slopes of the lava ridges furnish favorable catchment areas for surface 
waters, which are utilized by Hartford, New Britain, Meriden, and 
New Haven for city water supplies. Under the most favorable con- 
ditions the traps contain within themselves probably less than one- 
half of 1 per cent of their weight of water, and therefore may be dis- 
regarded as water reservoirs. (See PL IV, B.) 

WATER IN BEDDING PLANES. 

CONDITIONS OF OCCURRENCE. 

The sandstone, conglomerate, and shale of Connecticut, although 
differing markedly in texture, in extent and uniformity of bedding, 
and in structural relations, are alike in being water-laid deposits. 
They constitute a series of parallel strata separated by more or less 
definite bedding planes, whose location, extent, and character exert 
a predominant influence on the water supply of the State. If the 



108 UNDERGROUND WATEE RESOURCES OF CONNECTICUT. 

strata composing the Triassic were all of one type and homogeneous 
the ground water would be uniformly distributed, but owing to the 
different degrees of permeability possessed by the sandstone and shale 
the water tends to concentrate along definite horizons. For example, 
a bed of impervious shale overlain by sandstone allows water to accu- 
mulate in the upper strata. The water occupying the spaces between 
the sandstone grains will find it easier to move along the bedding 
plane than to penetrate the shale, and if the plane is exposed on a 
hillside or in an artificial opening a stream or seepage of water will 
likely be developed. (See fig. 5.) Shale is the most impervious rock 
in the sedimentary series and sandstone the most pervious, and to- 
gether they form the best reservoirs, but water will occupy the bed- 
ding plane between sandstone and lava, or between sandstone and 
conglomerate, or between two beds of the same strata. The bedding 
planes are not usually actual cavities visible to the eye, but rather 
planes of parting through which water moves by capillarity. In some 
places, however, the solvent action of water operating for thousands 
of years has widened the cracks to a fraction of an inch, and in a very 
few localities definite stream channels several inches in height have 
been developed through which water pours as small-sized rills. 

That water occupies these bedding planes in large amount is abund- 
antly shown by direct observation and by the experience of well 
drillers. In one of the Portland quarries, where pits 200 feet in depth 
have been opened "water everywhere emerges from along the bedding 
planes, especially along the shaly partings, where, dripping down, it 
darkens the quarry walls over large surfaces. " a In 1906 an exposed 
rock wall 75 feet in height in this quarry showed water entering from 
the bedding planes in large amounts, but none coming from the joints 
or oozing from the rock surface. In dozens of springs within the 
sandstone area the water issues from the contact between strata of 
varying texture and composition. 

The experience of well drillers leads to the same conclusion. C. L. 
Wright, of Augurville, who has sunk many wells in the sandstone, 
finds that the water comes from "flat seams" — that is, bedding planes 
at the "juncture of firmer rocks overlain by loose-textured rocks" — 
and that water frequently passes from these planes as a "sheet ex- 
tending entirely across the drill hole." A. A. Murray, of Middletown, 
reports that the largest amount of water "is to be encountered in hard 
rock directly at its contact with shale." In the vicinity of Hartford, 
according to C. L. Grant, the "usual water horizon is in the sandstone 
directly above the shale." 

That water circulates freely along definite bedding planes is shown 
by the manner in which wells that are located in proximity tend to 
influence one another. For example, five wells of the Electric Light 

a Stone, vol. 9, 1898, pp. 42-43. 



GROUND WATER IN TRIASSIC SANDSTONES AND TRAPS. 109 

Company in Hartford, sunk in sandstone and shale to a depth of 200 
to 225 feet and situated 40 to 50 feet apart, are all affected when 
water is pumped from any one, apparently because they draw their 
water from the same bedding plane. Other interesting evidence of 
the presence of water in bedding planes and its movements along these 
planes is furnished by two wells at the sanitarium 2£ miles northwest 
of Wallingford. One of the wells became contaminated by gasoline 
from a buried tank, and shortly afterward the other, 225 feet distant 
in the direction of the slope of the rock, became contaminated also. 
The polluted water had apparently traveled down the tilted bedding 
plane between sandstone layers. 

Another proof of the circulation of water along bedding planes is 
found in the fact that the rock bounding these planes is decomposed 
by the action of chemicals carried by subterranean waters. In quar- 
ries and railroad cuts where these bedding planes are exposed they 
usually appear as lines or zones of discolored rock, but in many places 
there is a distinct layer of leached and disintegrated material that has 
formed in place by slowly moving ground water charged with carbon 
dioxide and other chemical reagents. 

BLACK SHALE. 

Probably the most impervious rock within the Triassic area is the 
black bituminous shale which occurs as a member of the "Posterior" 
sandstones. (See p. 39.) In the vicinity of Hartford this shale has 
been penetrated by wells at a number of localities and at different 
depths, and it rarely fails to define a water horizon of great impor- 
tance. The logs of wells shown in figures 16 and 17 were furnished 
mainly by C. L. Grant and demonstrate two interesting facts — (1) 
that the water-bearing strata may be shale, as in the Newington, 
Allyn House, and Goodwin Park wells ; or sandstone, as in the Bloom- 
field wells; or conglomerate, as in the Windsor street well; and (2) 
that the typical posterior black shale, unmixed with sandy layers, is 
a water-confining bed of exceptional impermeability, even where only 
10 feet in thickness. The well of F. C. Dininy obtains its principal 
water supply at 256 feet below the surface and little water was en- 
countered at a greater depth. 

W^TER IN JOINTS. 

VERTICAL AND HORIZONTAL JOINTS. 

As explained on pages 37-38, all rocks are traversed at relatively 
short intervals by cracks or seams which serve to mark the rock 
surface into polygons and break it up into blocks of various sizes. 
These are the joints in rocks, and their presence and distribution are 
important factors bearing on the water supply of Connecticut. 



110 UNDERGROUND WATER RESOURCES OF CONNECTICUT. 



Hard pan 4 



lied shale 42 



Red shale 146 



Conglomerate ... 61 



Red shale 118 






256 Water. 
226 



Red shale 


5 
9 

31 

8 
2 

22 

4 

8 
8 

8 

1 


— ■■ — - - 


5 


Sandstone and grit 




Black shale with clay 


~-~- r ~-^< 


40 


Red sandstone 




Black shale and sandstone . . . 
Black shale 




HIl 


50 


Black and clay shale 


72 
76 
84 
92 


Black shale 


Brown-black and clay shale 
Sandstone, black shale, and 


blue clay shale 


te^ 


100 

101 Water. 


Veryblackcarbonaceousshaie 



Mud conglomerate. 



a.' •'.{ 

, <r • O « .• 

°<b . • o 
°A"o o' 



r O o ■ O. 



287 
299 



Figure 16.— Well logs showing influence of Triassic black shale in determining water horizons. 1, Well of 
F. C. Dininy, Windsor street, Hartford; water stands at 95 feet when well is pumped; yields 40 gallons a 
minute at 150 feet. 2, Well of H. C. Douglass, Bloomfield; flows 2 feet above surface; data furnished by 
owner. 3, Allyn House well, Hartford. 



GROUND WATER IN TRIASSIC SANDSTONES AND TRAPS. 



111 



The joints in Triassic sandstone, conglomerate, and shale intersect 
at various angles, both in the vertical and in the horizontal plane, 
and many of the blocks which they bound are wedges of large or 
small size. Numerous measurements of the inclination of joint 
planes show that they stand commonly at high angles approaching 
the vertical. In the Fairhaven tunnel the prominent joints dip 
between 65° and 86° S. In the railroad cut north of Yalesville and 
in several other localities the dip of the main joints is less than 10° 
from the vertical. Approximately three-fourths of the conspicuous 
joint planes noticed at sixteen localities in Triassic sedimentary 



Soil 29 


^r= 


29 

77 
95 

125 
142 

164 

189 Water. 
206 

250 


Soil 3 

Clay and 
hardpan 38 

Shale 6 

C o nglom- 
erate ... 40 

Shale 68 

Shale and 
sandstone 28 

Shale 33 


lHKr£ 


3 

41 

47 

87 Water. 

154 Water. 
155 

183 

187 Main 
water. 


Soil 43 

Red shale. 74 

Black 
shale ... 25 

Red shale. 43 

Black 
shale ... 15 


1^3? 








Water. 




— 


43 




== 


Soft red 
sandstone 48 


'.-'OXO'.o 

. o o. o • o : 

■o'.O'.o'.O 

"o • o <?" • 

.'..o'.o'.O. 

p';«'.o.'. 






z — 




Hard red 








llllllll 




Blue slaty 
shale ... 30 


=| 









117 Water. 







| 


Sandstone 17 




u 




Blue shale 22 


— 


142 




~zs 




Red shale. 25 


^^= 










Hard black 
shale ... 17 


Tl T ' II 
1 ll 1 ll ill 


185 
200 










E 




Red shale. 44 







Figure 17.— Well logs showing influence of Triassic black shale in determining water horizons. 1, Flowing 
well at Goodwin Park, Hartford. 2, Well of L. A. Storrs, Bloomfield. 3, Well of Dr. A. B. Johnson, 
Newington; yields 40 gallons a minute. 

rocks are between 70° and 90° from the horizontal. There are, 
however, numerous fractures which are nearly or quite parallel to 
the planes of stratification and which serve to break the rock into 
still more irregular and indeterminate fragments. These hori- 
zontal joints are in many places approximately parallel to the sur- 
face of the ground, and where they cross the bedding planes it is 
usually at an angle of less than 25°. 

Joints, both vertical and horizontal, are more common and more 
conspicuous and intersect at a larger number of angles in conglomer- 
ate and coarse sandstone than in shales. In fact, large regular blocks 
of conglomerate are quarried in very few places within the State. 



112 UNDEKGROUND WATER RESOURCES OF CONNECTICUT. 

In the sandstone quarries the joints are fairly regular and evenly 
spaced. In the long exposure of shaly sandstone in the gorge at 
South Meriden vertical joints are rare. Near Mill Rock joints in 
fine sandstone start, branch, and die out within a few inches, and in 
a number of localities joints traversing sandstone and conglomerate 
stop abruptly on reaching a stratum of shale. (See below.) 

DIRECTION AND CONTINUITY OF JOINTING. 

In the Portland quarry the prominent joints run N. 50° E., N. 
60° E., N. 75°-85° E., and N. 20° W.; in the vicinity of New Haven 
the chief joints extend east and west, N. 70°-80° W., N. 20° W., N. 
15°-20° E., and N. 50° E.; at West Granby, N. 80° W., N. 35° W., 
N. 10° E., and N. 20° E.; at West Cheshire, N. 80° W., N. 50°-60° 
W., N. 30° W., N. 10° E., and N. 55°-60° E. In the Pomperaug 
Valley Hobbs a found four major directions of jointing — N. 34° W., 
N. 5° W., N. 15° E., and N. 54° E. Although these uniform joint 
directions indicate some cause operating throughout the Triassic 
areas, there are many local variations, and in each region prominent 
cracks occur which do not correspond with the more common joints. 
For practical purposes each locality must be studied separately. 

Some of the more prominent joint planes have been traced on the 
surface for several hundred feet and from the top to the bottom of 
the deepest quarry and railroad cuts. A few doubtless extend paral- 
lel to fault lines for some thousands of feet. Most of the joints 
observed, however, appear as open cracks for distances rarely exceed- 
ing 50 feet, though they may extend for great distances, both ver- 
tically and horizontally, as invisible parting planes. 

SPACING OF JOINTS. 

In the outcrops of sedimentary rock examined there was found 
great irregularity in the number and distribution of joints. In 
places the joints are 50 to 60 feet apart; elsewhere ten to twenty joints 
occupy 50 feet of wall space. In most large outcrops there are zones 
along which joints are crowded at intervals of less than an inch, and 
on weathered surfaces and in cuts where blasting has been carried 
on the rock is shattered into fragments a few inches in thickness by 
a multitude of intersecting joints. Outcrops of red and black shale 
occur in which the horizontal joints have separated the rock into 
chips or flakes that could be removed with a shovel. It is evi- 
dent that in such rock ground water would circulate freely and be 
stored in large quantities. In the Portland quarries the main sets 
of vertical joints are 30 feet or more apart; at the north end they are 
35 to 100 feet apart; and nowhere in the quarry were joints of the 

a Hobbs, W. H., Twenty-first Ann. Rept. U. S. Geol. Survey, pt. 3, 1901, p. 100. 



GROUND WATER IN TRIASSIC SANDSTONES AND TRAPS. 113 

same series observed nearer than 7 feet from each other. In the 
railroad tunnel at Fairhaven the larger joints are about 25 feet apart 
and converge at low acute angles and branch out. At Pine Rock 
and West Rock the joints of all kinds average about five to a linear 
yard. The spacing of joints and their angle of inclination are the 
factors which determine the number contributory to a well. 

Both vertical and horizontal joints are wider, more numerous, 
and more closely spaced near the surface than farther down. In one 
quarry observed by the writer the upper 30 feet of Wall had nearly 
twice as many horizontal joints as the second 30 feet. The effect 
of joints is to greatly favor the absorption of water, but this must 
be a surface phenomenon, as the joints die out with increasing depth. 
In Connecticut large open joints are probably rare at depths exceed- 
ing 200 feet. 

OPENING OF JOINTS. 

. Some joints at the earth's surface and probably all joints at con- 
siderable depths are tightly closed and are more nearly planes along 
which the rock might be broken than open cracks. Many joints, 
however, are a fraction of an inch wide, some are 1 inch to 2 inches 
wide, and in the Blakeslee quarry horizontal joint zones 3 to 4 inches 
wide are found. One crack in this quarry which is 2\ inches in 
% width at the top was so narrow at the bottom that a sheet of note 
paper could not be inserted. Many joints exposed in quarry walls 
are filled with decomposed rock through their extent, and experi- 
ence in well drilling proves that decomposition extends to consider- 
able distances and serves to enlarge cracks to an important degree. 
(See pp. 73-74.) Where two joints intersect or where one crosses a 
bedding plane a channel may be developed by removing the disinte- 
grated rock which forms the boundary planes. (See fig. 18.) In 
one of the Portland quarries the water enters in good-sized streams 
from vertical joints to an amount estimated at 250,000 gallons 
daily. Such freedom of circulation would account for the water- 
laid sand found in joints at Hartford 20 feet below the surface. 
Numerous small joints, however, furnish more abundant and uni- 
form water supply than a few large open fractures. 

JOINTS IN TRAP. 

The direction, continuity, and inclination of cracks in the trap 
of the Triassic area are essentially the same as in sandstone. Expo- 
sures of trap rock are invariably characterized by well-developed 
vertical joints intersecting one another in all directions in vertical 
planes and dividing the rock into a series of polygonal blocks. This 
type of jointing undoubtedly is more conspicuous in exposures than 
it would be in unweathered ledges, yet the structure is developed in 
463— irr 232—09 8 



114 



UNDERGROUND WATER RESOURCES OF CONNECTICUT. 



deeply buried rock and occasions trouble in drilling, owing to the 
breaking off of angular blocks that wedge the tools. 

The opening of joints in trap and their value as reservoirs are 
practically the same as in the denser crystalline rocks described in 
Chapter IV (pp. 54-103). 

WATER ALONG FAULT LINES. 

Faults in rock are joints or cracks along which the strata have 
moved up or down or sidewise. The amount of displacement may 
be a fraction of an inch or thousands of feet, but as a rule there is a 
complete break in the continuity of the strata and a more or less 
open crack to mark the line of rupture. Few faults are single clean- 
cut breaks ; more commonly they consist of a number of breaks that 




Fault Tone 
Figure 18.— Sketch showing fault zones in sandstone. 



Fault zone 



result in shattering the rock along a line some feet in width, forming 
a zone of material arranged as a confused mosaic of loose or 
cemented fragments. 

The structure of fault zones is favorable for the absorption of 
large quantities of ground water, which may be readily recovered. 
(See fig. 18.) Many springs in Oregon, the hot springs of the southern 
Appalachians, Saratoga Springs, etc., are located along faults, and 
the character of their waters is due to the great depths from which 
they come. The relation of springs to fault lines is a well-known 
phenomenon in Connecticut and some striking instances have been 
described by W. H. Hobbs. a At one place in the Pomperaug Valley 
eight springs occur within a distance of 60 rods, all located on a single 



a Twenty-first Ann. Rept. U. S. Geol. Survey, pt. 3, 1901, pp. 91- 



GROUND WATER IN TRIASSIC SANDSTONES AND TRAPS. 115 

fault line. Near South Britain a number of springs are located at 
the intersection of two or more fault lines. Where fault lines are 
exposed in cuts and quarries the circulation of water in them is 
shown by actual seepage, by growth of plants, and by a zone of 
decomposed rock, formed by the solvent and oxidizing power of the 
ground water carrying carbon dioxide, etc., in solution. The rela- 
tion of faults to Water supply is well illustrated in the Middlesex 
quarry. Here the principal water carrier is an oblique fault zone 6 
inches to 1 foot wide, which not only absorbs much water from the 
earth's surface but is also the main artery receiving supplies from 
bedding planes one-fourth to one-half inch wide. This fault con- 
tains probably 15 per cent of open space available for water storage. 
Examples of wells located on faults are those of the Hartford Light 
and Power Company and of Armour & Co. at Hartford. The. wells 
at the New York, New Haven and Hartford power house and 
the Berlin Brick Company and the Yale Brick Company's works, 
Berlin Junction, and at Hotel Russwin, New Britain, are advantage- 
ously located near fault zones. 

RECORDS OF WELLS IN TRIASSIC SANDSTONES, CON- 
GLOMERATES, AND SHALES. 

The records of wells on the following pages have been selected to 
show the conditions controlling the recovery of ground water in the 
Triassic sediments of Connecticut. 

a Water-Supply Paper U. S. Geol. Survey No. 67, 1902, p. 80. 



116 



UNDERGROUND WATER RESOURCES OF CONNECTICUT. 



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GROUND WATER IN TRIASSIC SANDSTONES AND TRAPS. 



117 



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118 



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GROUND WATER IN TRIASSIC SANDSTONES AND TRAPS. 



119 



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120 



UNDERGROUND WATER RESOURCES OF CONNECTICUT. 



























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GROUND WATER IN TRIASSIC SANDSTONES AND TRAPS. 



121 



























ooc 

O00C 
CJ H CN 


s 


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cn 


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boiler. 

Factory 
purposes, 
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stock. 

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122 



UNDERGROUND WATER RESOURCES OP CONNECTICUT. 



1 

a 








14 feet of soil, 36 feet of 
trap, 1£ feet of sedi- 
mentary rock. 

See analysis, p. 177. 






















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to 

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GROUND WATER IN TRIASSIC SANDSTONES AND TRAPS. 



123 



























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124 UNDERGROUND WATER RESOURCES OF CONNECTICUT. 



NOTES.a 

1. Passed through 20 feet of gravel, 25 feet of quicksand, 25 feet of gravel and 
hardpan, and 30 feet of red shale, in which the water was obtained. The water comes 
in slowly and carries fine sediment. 

12. A little water was obtained at a depth of 50 feet and the water rose within 12 
feet of the surface and remained at this level until a large supply was struck at a 
depth of 325 feet, when the water level lowered to 35 feet below the surface. 

24. Passed through 17J feet of soil and through 54 feet of trap ending in a hard red 
rock, probably sandstone. The source of the water is at the contact between the trap 
and the sandstone. 

26. This well was drilled through sandstone into trap rock and the water enters 
above the trap. 

38. This well is 52 feet deep and 6 inches in diameter, 40 feet of its depth being in 
the rock. The water rises within 7 feet of the top, a good many feet above the level 
of Connecticut River, which is only a stone's throw away. The pump raises 31 
gallons a minute, which lowers the well 8 feet, but no farther. The water is moder- 
ately hard, has been used in boilers, and keeps a uniform temperature of 51° F. the 
year round. 

47. Soil and sand, 20 feet; blue clay, hard and dry, 30 feet; clay and red quick- 
sand, 10 feet; fine red quicksand, very shifting and hard packed, with a thin layer 
of saturated gravel at 118 feet from the surface, 60 feet; quicksand, 30 feet; gravel, 
8 inches; sandstone, varying in hardness at different depths, 74^ feet. The water stood 
at 8 feet below the surface in the first soil and sand stratum but dropped to 30 feet 
below the surface after the 30-foot layer of clay was penetrated. 

64. This well was drilled in 1863 by Col. Samuel Colt and flowed until 1898, when 
a well was drilled 1,000 feet farther north and the Colt well stopped flowing the next 
day. 

74. This well was drilled by C. L. Grant, who furnished the following data: Depth, 
250 feet; diameter, 8 inches. The well is in rock and flows. Elisha Gregory, a well 
driller of New York City, states in his "Torpedo circular" that the well was torpedoed 
by him at a later date and that as a result the yield was increased from 15 to 35 gallons 
a minute. It is reported that the quality of the water was injured by the process. 
Inquiry at the office of the company shows that at last accounts the water was not 
used for anything, so heavily is it charged with mineral matter. For analysis see 
table on page 177. 

79. The 620-foot well of this company gives a more copious supply of water in rainy 
than in dry weather. The water contains too much calcium sulphate for boilers but 
is used for condensers. This well is said to have diminished the yields of four wells, 
each about 200 feet in depth, sunk for the same company. 

80. It is stated that 400 gallons a minute have been pumped from this well without 
making any apparent impression on the water level. The well is 462 feet deep. 

81. Depth, 420 feet. The water flows 1 inch over the top of the pipe when allowed 
to stand, which brings the water level above a large part of the neighboring land. 
The ordinary yield is 150 gallons a minute, the well being pumped continuously. 

f81J. Depth, 500 feet; diameter, 8 inches. The water rises to the surf ace of the engine- 
room floor, and is pumped at the rate of 75 gallons a minute. The well is drilled in 
the "Upper" sandstones, but unquestionably pierces the "Posterior" trap sheet, 
which outcrops at no great distance to the west. 

85. The water in this 457-foot well will rise 15 feet above the top and yield 205 gal- 
lons a minute at the surface. Pumping 600 gallons a minute for ten hours lowered the 
water level to 12 feet below the surface, where it remained constant. 

a Descriptions of wells marked " f " are taken from Water-Supply Paper 110. 



GROUND WATER IN TRIASSIC SANDSTONES AND TRAPS. 125 

f91. Depth, 300 feet; diameter, 4 (?) inches. The water flows over the top of the 
pipe at a rate of probably 10 to 12 gallons a minute. The water is hard and is used 
for drinking purposes only. The well lies entirely in the rock, which, in the stream 
near by, is seen to be rather loose in texture and to be filled with fragments of the 
crystalline rocks of the neighboring eastern highland. 

flOO. There are on the premises of this company five artesian wells, all 8 inches in 
diameter, from 250 to 300 feet deep, and bored into red sandstone, which at this 
place lies from 6 to 10 feet below the surface of the ground. The yield was measured 
when they were first bored, and varied in the different wells from 10 to 80 gallons a 
minute. The supply thus measured was obtained by means of an ordinary suction 
pump, which, operated at the rate named, lowered the water about 25 feet below the 
surface — as low as it could be pumped with that form of apparatus. A few years ago 
a system that works by compressed air and forces the water from depths of 70 to 90 
feet was installed. This apparatus gave a very greatly increased output, which now 
supplies all the needs of the company. The water from these wells is all discharged 
into one large cistern, from which it is circulated through the factory. It is not easy 
to determine exactly the amount of water used, but it is estimated as between 75,000 
and 100,000 gallons a day of ten hours. A much larger quantity than this could be 
obtained if needed. The water is satisfactory for manufacturing purposes except for 
use in boilers. 

101. A well 560 feet deep, penetrating 9 feet of soil, 18 inches of gravel,, 90 feet of 
quicksand, and 459£ feet of rock. 

103. Drilled through 24 feet of clay, 20 feet of sand, 8 feet of clay, 50 feet of sand- 
stone. 

113. Depth, 500 feet. At a depth of 40 feet in sandy shale the well gave a small 
flow and drained an old dug well, 25 feet deep, in similar material. The well passed 
through about 300 feet of sandstone above bluish sandy shale and through a soft car- 
bonaceous shale at about 400 feet. The well then passed through conglomerate and 
ended in blue clay shale. No water was struck below 40 feet and the flow ceased after 
a charge of nitroglycerine was fired in the well. 

fll6. Depth, 152 feet; depth of water when lowest, 130 feet, but if the well is a 
allowed to stand the water flows at the level of the engine-room floor, which is 10 feet 
below grade. The ordinary consumption is fully 10,000 gallons a day. The water 
can be used for all purposes. The well penetrated 140 feet of sandstone, etc., without 
finding enough water to keep the drill wet, but at that depth the drill became jammed 
in what appeared to be a crack about 2 inches wide, and an ingress of water followed 
the loosening of the drill. The apparent breadth of the crack may in reality be due 
rather to the presence of soft, decomposed rock along the joint plane than to an actual 
opening of the size indicated. 

119. Drilled by the company in 1893, but no water was obtained except from 
surface seepage. It is 4,000 feet deep. 

126. Depth, 572 feet. Penetrated 264 feet of quicksand and clay, the clay occur- 
ring mainly in small layers but with one 25-foot stratum -above the rock. 

163. Passed through 6 feet of loam, 76 feet of sand, 2 feet of gravel, and 34 feet of 
sandstone. 

fl65 an*d 166. Town water supply of Suflield, owned by Paulus Fuller. No. 165 
is 230 feet deep and has a diameter of 6 inches; No. 166 is 240 feet deep and has a 
diameter of 8 inches. The two wells together pump at the rate of 300 gallons a min- 
ute into a standpipe containing 293,000 gallons. The water rises within about 60 
feet of the surface and is rather highly mineralized. It can be used in boilers, how- 
ever, but gives some scale. The wells enter rock about 10 feet below the surface. 

188. Depth, 131J feet. Passed through 70 feet of soil, consisting of light sandy 
soil, light gravel, coarse gravel, and hardpan, and penetrated 61 \ feet of soft red 



126 



UNDERGROUND WATER RESOURCES OF CONNECTICUT. 



sandstone. The water naturally stands at 26 feet below the surface, and on being 
pumped out to a depth of 75 feet gave the following flows, as recorded by Mr. Bidwell: 



Depth 


Water 


Time 


Feet per 


(feet). 


(feet). 


(hours). 


hour. 


75 


5 


1 


20 




[ 3.5 


I 


14 


64 


\ 11.5 


1 


11.5 




18. 5 


2f 


6.7 


52J 


4.5 


i 


9 


48 


2.5 


1 


2.5 



fl90. Depth, 386 feet; depth of water, 326 feet; diameter, 6 inches. The pump 
yields 30 gallons a minute, which lowers the water 5 feet. The well passed through 
sand, 17 feet; clay, 56 feet; hard red gravel, 50 feet; the remainder in sandstone with 
the exception of two layers of "slate." Four analyses of the water have been made, 
according to which it ranges from moderately hard to excessively hard. It would 
seem that the water is free from organic impurities, but shows sulphate of lime to 
the extent of 590 parts to the million. It is extremely hard to the soap test. When 
first drawn the water is said to give off a strong odor of hydrogen sulphide. 

tl91. Depth, 113 feet; diameter, 6 inches; yield, 50 gallons a minute. Drilled 
in the bottom of an old open well and lies in the rock. The water is good only for 
drinking and garden use. It is said that when the well was first drilled the water 
had a very strong odor, which disappeared after the well had been used awhile. 
Data furnished by King & Mather. 

Additional records of wells in the sandstone area of Connecticut. 

[These wells were drilled by C. L. Grant, who has furnished the records. They presumably derive their 
water from sandstone, though a few may be in trap.] 



No.o 



10 

11 
12 
13 
14 
15 
16 
17 
18 
19 
20 
21 
22 
23 

24 

25 
*2R 
27 
28 
29 
30 
31 
32 



Town. 



Berlin. 



....do 

....do 

....do 

Bloomfield. 

....do 

....do 

....do 



Farmington. 

....do 

....do 

....do 

Ham den 

....do 

....do 

....do 

....do 

....do 

....do 

....do 

....do 

....do 

Hartford 



Locality. 



Whitney ville. 

....do 

....do 

....do 

....do 



Mount Carmel. 

....do 

....do 



Owner. 



New York, New Haven and 

Hartford R. R. 

Berlin Brick Co 

do 

Yale Brick Co 

Mrs. A. S. Sage 

M. J. Bradley 

Grover Brown 

Mrs. G. A. Cadwell 

Mrs. E. A. Smith ■ 

T.H.&L.C. Root 

Lewis A. Storrs 

Frank Hotchkiss 

John H. Burton 

W. F. Downer 

Edw. Davis 

Geo. W. Ives 

Mr. Johnson 

A. E. Woodruff 

Chas. Wheeler 

Sylvester Peck 

Newton Archer 

Wm. Ben ham 

Hartford Woven Wire Mattress 

Co. 

Retreat for Insane 

W.C. Wade 

Ropkins & Co. Brewery 

Long Bros 

H. E. Patten 

Hartford Light and Power Co 

do 

do 

do 



Depth 


Depth 


of 


to 


well. 


water. 


Feet. 


Feet. 


300 


22 


60 


11 


70 


8 


100 


19 


86 


18 


47 


12 


31 


17 


61 


61 


290 


50 


190 


55 


208 


41 


100 


29 


50 


10 


67 


27 


56 


9 


65 


13 


58 


25 


50 


12 


50 


17 


36 


21 


38 


18 


68 


28 


246 


16 


180 


24 


125 


11 


200 





200 


11 


110 


10 


200 


2 


228 


1* 


201 


n 


200 






Yield 

per 

minute. 



Gallons. 
120 



3 
10 

20 
50 
60 
29 
150 
120 
150 
120 
150 



a For additional details, see page 128. 



GROUND WATER IN TRIASSIC SANDSTONES AND TRAPS. 127 

Additional records of wells in the sandstone area of Connecticut — Continued. 



No. 


Town. 


Locality. 


Owner. 


Depth 

of 
well. 


Depth 

to 
water. 


Yield 
per 

minute. 


33 


Hartford. . . . 




Herold Capitol Brewing Co 


Feet. 

300 

318 

240 

159 

140 

170 

155 

57 

67 

110 

37 

62 

60 

37 

50 

63 

49 

110 

50 

50 

48 

35 

28 


Feet. 
Flows. 
25 
25 
15 
29 
32 
25 

9 
19 
23 


22 
20 


20 
27 
20 
75 
10 
11 
21 
17 
12 
16 
11 
13 
30 
12 
15 
10 
30 
18 
25 

5 

40 
18 
12 
38 

7 
13 
49 
18 

1 
Flows. 

3 

12" 

112 
35 
18 
15 
28 

2l" 

14 

6 

2 

12 

22 

i25" 

36 
34 
24 


Gallons. 
250 


34 


do 




50 


rtf 


...do... 




Geo. M. Brown 


45 


36 


do 






15 


V 


.do... 






10 


38 


.do.... 






16 


39 


...do 




Hotoph & Carlson 


12 


40 


....do 




Frank S. Tarbox 

do 


5 


41 


do... 




2 


4? 


.do... 




E. G. McCune 

Geo. F. Hubbard 

do 


12 


43 


...do 




7 


44 


do 




14 


45 


.do... 






3 


46 

47 


do 

...do 




Yv r . S.Mather 

Wm. O'Brien 


ii 


48 


do 






8 


49 


do... 






11 


50 


.do... 






5 


■SI 


...do 






9 


5? 


do 






8 


53 


do 




C. L. Bailey 


11 


54 


.do 




H. G. Abbey... 


7 


55 


..do 






5 


56 


.do 




B. L. Chappell 


50 

50 

37 

60 

50 

50 

50 

70 

65 

75 

53 

75 

40 

195 

200 

60 

250 

80 

237 

173 

50 

200 

254 

103 

300 

245 

75 

67 

24 

91 

159 

73 

83 

102 

28 

50 

48 

25 

212 

331 

61 

66 


12 


57 


...do 




Geo. E. Hurd 


8 


58 


....do 






10 


59 


do 




Dr. W. Crane 


2 


60 


.do 






6 


61 


do 

.....do 

do 






11 


6? 




8 


63 


F. H. Sevmour 


8 


64 


do 




Geo. J. Maher 


13 


65 




A. M. Weber 


5 


66 


.....do \ 


R. Balinson 


9 


67 


A. B. Calef 




68 




W. E. Bradley 




69 


.do ! 




40 


70 


.do 




32 


71 




.do ... 


12 


7? 


..do 1 


J. P. Curtis 


10 


73 


" ..do ( 




6 


74 


do 

do ! 


A.W.Stanley 


5 


75 


Coburn Land and Lumber Co. . . 
Geo. W. Ives & Son 


47 


76 






77 


...do i 


.do 


10 


78 


..do ! 




65 


79 


....do 1 . . 




60 


80 


do L 




58 


81 


do .. 


.do 


45 


8? 


do 


H. H. Olds & Co 




83 


Newington ' 


Center school district 


20 


84 


do 


E. E. Pimm 


5 


85 


do 1 


Mrs. S. F. Robbins 


12 


86 


do 




Newton Osborn 


18 


87 


do 




J. G. Paradise 


12 


88 


North Haven 




F. L. Stiles 


35 


89 


do 




I. L. Stiles & Son 


30 


90 


Plain ville 




John Coughlin 




91 


do 




N. Terrell 


8 


9? 


do 




P. Horan 




93 


Rocky Hill 




J. K. Green 


4 


94 


Sims bury 




W. L. Cushing 


17 


95 


..do 


Tariff ville. 


Connecticut Tobacco Corporation. 
Mrs. G. C. Willoughby 


30 


96 


do 

Southington 


do 


4 


97 


D . Green 


5 


98 


....do 




iEtnaNutCo 




99 


Suffield 




E. A. Fuller 


40 
63 
45 
48 
60 
135 
100 
67 
90 
40 
110 
135 
53 


6 
14 

6 
18 
13 

9 

6 
45 
118 
Flows. 
15 
20 

9 


6 


100 


do 

do 




Dr. M. T. Newton 


10 


101 




3 


10? 


do 




3 


103 


do 




4 


104 


do 


West Suffield 


Frank S. Root 


12 


105 


Wallingford 

do 

do 

do 

West Hartford.... 


Yalesville 


G. I. Mix & Co 


40 


106 


do 

do 

Quinnipiac 


J.H.Yale 




107 


C. W. Michaels 




108 


C. T. Stevens :. 


4 


109 


Jas. Thompson 


23 


110 


do 




E. C. Wheaton. 


35 


111 


do 




Mrs. Kate Gallagher 


3 



128 UNDERGROUND WATER RESOURCES OF CONNECTICUT. 

Additional records of wells in the sandstone area of Connecticut — Continued. 



No. 



Town. 



Locality. 



Owner. 



Depth 


Depth 


of 


to 


well. 


water. 


Feet. 


Feet. 


30 


15 


52 


13 


175 


15 


100 


13 


51 


23 


195 


39 


30 


2 


70 


30 


101 


12 


150 


100 



Yield 

per 

minute. 



112 
113 
*114 
115 
116 
117 
118 
119 
120 
121 



West Hartford. 

....do 

....do 



....do 

....do 

....do 

Wethersfield. 

....do 

Windsor 

....do 



Elmwood. . 
do 



Poquonock. 



Geo. V. Briekley 

L.N. Burt 

P. H. Reilly 

D. F.Crozier 

Mrs. E. W. Talcott 

Jas. H. Waldron 

J. H. Rabbett 

Rev. Lynch 

C. D. Reed 

Connecticut Valley Tobacco Co. . 



Gallons. 
12 



NOTES. 

26. Depth, 200 feet; diameter, 6 inches; yield, 60 gallons a minute. The ordi- 
nary yield of the well is 25 gallons a minute and it flows if left standing. The 
water is too hard for boilers. 

114. Sunk in the "Posterior" trap sheet, which at this locality is comparatively 
thin. The thickness of the trap has not been determined, but at least two-thirds, 
and possibly three-fourths, of the depth of the well must be in the "Posterior" 
shales which underlie the sheet, and it is very probable that the water does not 
come from the trap at all, but from the underlying shale. 



WELLS IN TRAP. 

Owing to the rugged topography of the main trap ridges few 
houses are built on them and consequently few wells have been 
drilled in rock of this character. In the vicinity of Hartford there 
are several wells which have been sunk directly into trap and obtain 
yields of 2 or 3 gallons a minute. The greater number of successful 
wells in rock of this type pass entirely through the trap and obtain 
their supplies from the underlying sandstone or shale. 

All exposures of trap show an extraordinary development of 
jointing, and in cliffs, as at East Rock and West Rock in New Haven, 
the vertical joints cut the formation from top to bottom and usually 
show weathering, indicating the past action of water. In large trap 
exposures it is unusual to strike streams of water, which are so char- 
acteristic of the quarries in crystalline rocks, although it is said that 
in one of the Hartford quarries two days after a heavy rain water 
will begin to seep out of the joints at the base. 

The field evidence indicates that the chances are small for obtain- 
ing water by drilling on the higher parts of the trap ridges, as the 
rock is so completely fractured at the surface as to allow the water 
to pass through and escape at lower levels, and at a short distance 
below the surface the joints are too tight to admit water in quantity. 
On such ridges, however, supplies may generally be obtained by 
shallow dug wells in the overlying drift. 



GROUND WATER IN TRIASSIC SANDSTONES AND TRAPS. 129 

Some interesting wells in trap have been described a by M. L. 
Fuller and W. H. C. Pynchon, as follows : 

W. E. Pratt [Rocky Rill]. — This well is located in the thin " Posterior" sheet of trap. 
It was drilled in the bottom of an old open well, 20 feet deep, which entered the rock 
for a distance of 6 feet. From this point the well was drilled 30 feet through trap, when 
it broke into the underlying sedimentaries, which it pierced to the depth of 1£ feet. 
This well therefore gives a section of 14 feet of soil, 36 feet of trap, and 1£ feet of sedi- 
mentary rock — a total depth of 51§ feet. This brings the bottom of the well about 50 
feet above the surface of Connecticut River, which flows by it only a few hundred feet 
eastward. The diameter of the well is 6 inches and the maximum amount of water 
obtainable is a little less than 1 gallon a minute. The well pumps dry in thirty 
minutes. The water is fair for drinking, but is excessively hard. 

/. K. Green [Rochj Hill]. — Depth of well, 26 feet; depth of water, 25 feet; diameter, 
6 inches; yield not given. The well is in trap rock. Data by Grant. 

Hotel Russwin [New Britain]. — The depth of the well is 152 feet, and the depth of the 
water at the lowest 130 feet, but if the well is allowed to stand the water flows at the 
level of the engine-room floor, which is 10 feet below grade. The ordinary consump- 
tion is fully 10,000 gallons a day. The water is very pure and can be used for all 
purposes. 

[Wells at Cedar Mountain.] — The wells * * * at Cedar Mountain, southwest of 
Hartford, * * * are on the property of Dr. Gordon W. Russell, who sunk the wells 
largely as an experiment and who has shown much interest in scientific matters. The 
mountain is a part of the ridge of the ' ' Main " trap sheet, and has a maximum elevation 
of about 360 feet above the sea. Its western face is very steep, dropping 250 feet to the 
plain within a distance of two-fifths of a mile, and is actually precipitous near the 
summit. The eastern face slopes more gradually, dropping about 120 feet to the valley 
occupied by shales, about three-fifths of a mile distant. It is in all a typical trap ridge. 

Well A is an ordinary open well and was dug to supply the needs of the farmhouse. 
It was opened 9 or 10 feet to the rock, but the water became shallow in summer. It was 
then sunk 1 or 2 feet into the loose, greatly jointed surface trap and has since given an 
abundance of water for domestic uses. The supply, however, fluctuates regularly with 
the wetness or dryness of the season. From the well mouth the mountain side with its 
drift covering rises steadily for two-fifths of a mile to the west till it reaches the crest, 
which is about 100 feet above the well. The supply is clearly the surface water con- 
tained in the soil and in the heavily jointed upper surface of the trap, the source also 
of a little stream which lies a little farther up the ridge. 

Well B is located about 200 feet south of well A. It passes through 9 feet of soil and 
then through about 290 feet of trap rock, at which point the string of drilling tools 
wedged fast, possibly along a joint plane. The well is 6 inches in diameter. On 
illuminating it brightly for a considerable depth by light reflected from a mirror, it 
appeared that no water came into it except from the shattered upper surface of the trap 
sheet, as in well A. The drill had not entered the underlying sediments when the well 
was visited in 1902, notwithstanding the fact that the bottom of the well was much 
below the level of the western plain. 

Well C is located about three-fourths of a mile farther south and a little farther east 
than the other two wells. It has a depth of 103 feet. It was thought from the residue 
brought up by the sand bucket that the well entered the sedimentary beds below, but 
in view of the record of well B and the thickness of the "Main" sheet this is extremely 
doubtful. Water was struck at a depth of 38 feet from the surface in a joint, the yield 
being 32 gallons an hour. At the present depth the well is capable of giving 90 gallons 
an hour, the water probably coming through joints from a level below the well bottom 

a Water-Supply Paper U. S. Geol. Survey No. 110, 1905, pp. 88, 89, 100, 101, 103. 
463— irr 232—09 9 



130 TJNDERGKOTJND WATER RESOURCES OF CONNECTICUT. 

and rising to within 25 feet of the surface. During the drilling light was reflected down 
the bore and water was seen coming in through the trap, and in the opinion of the 
driller, Mr. H. B. King, of Hartford, from the downhill side. However this may be, 
we have here a well near the summit of the mountain whose bottom is above the level 
of the lowlands on either side, with water coming in through the trap and rising to a 
point about 175 feet above the plain three-fourths of a mile to the west and about 70 feet 
above the valley one-fourth of a mile to the east. The top of the well is abort 280 feet 
above sea level. 

PRACTICAL APPLICATIONS. 

YIELD OF WELLS. 

The sedimentary rocks of Connecticut possess large storage capacity 
between strata, in joints, along faults, and within the rocks them- 
selves, and it is but rarely that a well sunk into sandstone, conglom- 
erate, or shale does not obtain water from one or all of these sources in 
sufficient amount for domestic purposes. No enormous supplies run- 
ning into thousands of gallons a minute, such as are obtained else- 
where in the United States, are found, and in some parts of the State 
difficulty has been experienced in obtaining sufficient supplies for large 
manufacturing plants. Wells in sandstone offer the best chances for 
large supplies, shale coming second, and conglomerate third. A few 
wells in conglomerate at New Haven encountered dry rock from top 
to bottom of the drill hole. One well on George street, 500 feet deep, 
obtained no water after passing through the cover of glacial drift, and 
another well remained dry to a depth of 4,000 feet. Such wells should 
not be abandoned "without a thorough test of every water horizon, 
however small. The casing, if possible, should be raised above the 
level of the water-bearing bed, a pump inserted, and the supply meas- 
ured. When it is impossible to remove the casing, it can be destroyed 
at the water horizon by a shot of nitroglycerine, which will also at the 
same time tend to loosen up the surrounding rock and increase the 
flow. Supplies have frequently been developed at horizons which 
were not at first thought worthy of testing and which were originally 
drilled through without stopping and cased off." a Of the 194 wells 
recorded on pages 116-123, only 11, or 5.6 per cent, failed to obtain 
2 gallons a minute, the minimum amount desired for domestic pur- 
poses. Drillers are naturally averse to reporting well failures, yet 
considering the number of successful wells of which no records are 
available the above percentage is probably close to the facts. 

The average yield of 112 wells in sandstone reported in the tables 
is 21\ gallons a minute, the largest being 350 gallons and the smallest 
two-thirds of a gallon. The 107 wells included in the supplementary 
list furnished by C. L. Grant (pp. 126-128) have an average yield of 
26 gallons. As a rule, the well that encounters the largest number of 
joints and bedding planes has the largest supply of water, and there 

a Water-Supply Paper U. S, Geol, Survey No. 110, 1905, 



GROUND WATER IN TRIASSIC SANDSTONES AND TRAPS. 131 

is, therefore, an increased yield with increased depth. This state- 
ment, however, is true only for wells less than about 300 feet in depth 
(see below), and many exceptions are to be noted. A well which 
strikes a favorable bedding plane between sandstone and shale, or 
drains water from a contact of trap and sandstone, or strikes a fault 
zone may yield large amounts at slight depths. In fact, the w r ater 
moves so freely through the rock that wells sunk to lower levels or 
located more advantageously may drain a neighboring well, thus 
making it useless. (See pp. 108-109.) 

The abundant and uniformly distributed rainfall of Connecticut 
(see p. 24) and the freedom of circulation of ground w r ater in the 
Triassic sediments account for the slight variation in yield throughout 
the year. Few drilled wells in rock show seasonal variations. A 
few record a decrease in summer; in several others the supply has 
increased since the wells were dug. Mr. Grant is of the opinion that 
"in general, the wells in the Triassic area have increased their flow 
with age." This seems to be due to the enlargement of seams and 
joints caused by the washing out of the decomposed rock ("clay"). 
"Water from black shale," says Mr. Grant, "clears up in about two 
hours, but that from red shale remains cloudy for a week or two." 
In many wells the water has become clearer as the years have passed. 
The height at which water stands in the well is also remarkably 
uniform. 

DEPTH OF WELLS. 

Two geologic myths seem to have attained the dignity of facts in the 
popular mind; one is that ore veins increase in richness with increas- 
ing depth, the other that water is more abundant and of better 
quality in proportion as it comes from greater depth. So far as 
Connecticut's water supply is concerned, the facts are not in accord 
with popular opinion. Though water is drawn from sandstones at 
all depths between the surface and 800 feet, yet the greatest number 
of failures are in wells exceeding 400 feet in depth. The reason for 
decreased supply at greater depth is the decrease in the number of 
joints and the tightening of both joints and bedding planes. The 
average depth of 287 wells, including the three deepest, one of them 
4,000 feet, is 144 feet. At $2.26 a foot, which is the average cost of 
67 wells, the cost of the average well is $335.44. The depth to the 
principal water horizon is even less than the depth of the wells. In 
63 wells with an average depth of 127 feet the principal source of 
water was 97 feet below the surface. The depth to the surface of the 
water in 144 wells in sandstone averages 23 feet. Of the 314 wells 
recorded in sandstone, shale, and conglomerate, 75 per cent are less 
than 200 feet deep, 90 per cent less than 300 feet, and only 5.6 per 
cent more than 400 feet; 47 per cent, including some of the best 
wells in the Connecticut Valley ; are less than 100 feet deep. 



132 UNDERGROUND WATER RESOURCES OF CONNECTICUT. 

In view of these facts and in consideration of the increased diffi- 
culty and cost of deep-well construction, it is good practice to abandon 
a well that has not obtained satisfactory supplies at 250 to 300 feet. 
Two or three wells 200 feet deep could be drilled at the cost of one 
500-foot well, and the prospect of obtaining water would be greatly 
increased. In case a well is abandoned, the new location should be 
as far as possible from the old. In fractured rock favorable condi- 
tions may be found a few hundred feet distant. Wells in shale may 
be sunk to greater depth before abandoning the site, as is indicated 
by the fact that of sixteen deep wells in shale two are between 100 and 
200 feet deep, five between 200 and 300 feet, four between 300 and 
400 feet, two between 400 and 500 feet, and three more than 500 
feet. a 

QUALITY OF WATER. 

The table of analyses shows that the composition of water in Tri- 
assic strata varies greatly, for wells only a few hundred feet apart 
may show marked differences in mineralization. One reason for 
this can be traced primarily to the inclination of the strata. As the 
rocks dip eastward at an angle of 15° or more, the area tributary 
to each well is rather small; a 500-foot well, for instance, would have 
a supply basin of considerably less than one-sixth of a square mile. 
Therefore different wells are supplied from different sets of beds, 
which differ from each other in their composition and consequently 
in their effect on the water passing through them. In general, the 
waters of the Triassic are so highly mineralized as to be undesirable 
for boilers without purification, thus strongly contrasting with those 
obtained from wells in crystalline rock. (See p. 168.) They are not 
too hard for cooling, washing, and certain other manufacturing pur- 
poses, nor for domestic use. Many wells show 500 to 2,500 parts 
per million of dissolved solids, including not only incrusting carbon- 
ates, but also the more undesirable sulphates. The water percolating 
through sandstone and shale is usually harder than that in joints 
and in bedding planes, and water of different quality may come from 
each stratum. 

TEMPERATURE. 

The temperature of well waters is determined by the depth from 
which they are drawn. At depths less than 50 feet the temperature 
of the water will roughly vary with the temperature of the air, which 
for Connecticut is 45° for the spring season, 67° in the summer, 51° 
in the fall, and 36° in the winter. 6 Below about 50 feet the temper- 
ature increases at the rate of 1° for each 60 feet. 

a Water-Supply Paper U. S. Geol. Survey No. 110, 1905, p. 99. 

& These figures are based on the mean seasonal temperatures of Storrs, New Haven, and Cream Hill, 
Combined, for the years 1893-1903, 1873-1903, and 1897-1907, respectively, as given on pages 24, 25, 



GROUND WATER IN TRIASSIC SANDSTONES AND TRAPS. 



133 



HEIGHT OF WATER IN WELLS. 

Water in wells tends to reach a certain level, which remains con- 
stant with the exception of slight seasonal variations and changes 
produced by pumping. The height at which this water level stands 
depends on the character and permanency of the supply. In some 
wells the water stands at the rock surface, in others above or below 
that surface, and in a few it is under hydrostatic pressure and reaches 
the earth's surface as a flow. The topographic location is another 
factor in determining water level in wells, for, as shown in the table 
below, the water in valleys tends to rise above the rock floor, whereas 
about half of the wells on hills and slopes maintain a level within the 
rock. Considered as a whole, the water level in the Triassic sandstone 
stands 23 feet below the surface of the ground. 

Height of water in wells. 





Number of 

. wells 
averaged. 


Percentage with water level — 


Location. 


Below 

rock 

surface. 


Above 

rock 

surface. 


Even with 

rock 

surface. 


Hills 


28 
59 
29 


46.4 
28.8 
48.3 


50 
67.8 

44.8 


3.6 




3.4 




6.9 







FLOWING WELLS. 

As stated on page 49, the primary conditions for flowing wells are (a) 
strata capable of holding large amounts of water, overlain by strata 
which are relatively impermeable; (b) outcrops of the strata where 
they may receive the surface water, and (c) a suitable dip to the rock. 
All these conditions are present in the Triassic areas of Connecticut. 
Sandstone and shale are interstr a titled, forming the couple which 
produces artesian wells in the Dakotas, New Jersey, Texas, and else- 
where. Lava flows alternate with the. sandstones and shales, a con- 
dition which makes an artesian basin in parts of Idaho. a The edges 
of the water-bearing strata are well exposed, the rainfall is ample, and 
there is a dip to the strata of 15° or more to the southeast. Under 
normal conditions the Connecticut lowland would therefore form an 
unusually good artesian basin, and wells sunk anywhere along the 
western border of the Triassic area would procure large supplies, as 
showm in figure 19. This opportunity of obtaining artesian wells is 
almost entirely destroyed by two circumstances. First, the region is 
crossed by a series of faults and the strata are broken into huge blocks 
uplifted on the west side. The continuity of the water-bearing beds 
is therefore destroyed. But, even under these conditions, artesian 

a Russell, I. C.„ Bull. U. S. Geol. Survey No. 199, 1902, pp. 178-180. 



134 



UNDERGROUND WATER RESOURCES OF CONNECTICUT. 



basins of moderate extent (fig. 20) would be present were it not for 
the fact that the strata between the fault lines are cut by joints which 



fc- V->'~J^ r f ^ 






run in all directions and are but short distances apart, several being 
present in each 100 feet (fig. 21). The continuity of the beds is thus 



GROUND WATER IN TRIASSIC SANDSTONES AND TRAPS. 



135 



further disturbed and the existence of unbroken beds, either as water 
bearers or water retainers is made impossible. All the strata, includ- 
ing the lavas, have taken part in 
this faulting and jointing, with the 
result that instead of numerous 
flowing wells throughout the region, 
there are a few the waters of which 
rise slightly above the surface. 
Some of the flowing wells derive 
their water from local bedding 
planes in rock; the others from the 
contact of rock with the cover of 
glacial till. 



LOCATION OF WELLS. 

Two considerations will usually 
control the location of wells — the 
amount and the quality of the water 
desired. To insure good quality 
requires a location selected with 
reference to freedom from contami- 
nation by drainage from barns, cess- 
pools, houses, factories, etc. High 
ground with a surface cover of gla- 
cial material is a better location than 
bare rock. A well in low ground 
will usually yield more water at less 
expense, but the danger of contami- 
nation is greater. When it is pro- 
posed to construct a well, the con- 
dition of existing wells in that 
vicinity or in the same rock type 
should be studied with care. The 
direction, opening, continuity, and 
number of joints in the rock should 
be observed ; also the dip or incli- 
nation of the strata and the pres- 
ence of beds of shale or trap. 

It is to be remembered that water 
in bedding planes passes up as well 
as down an inclined surface. The 
usual experience, as stated by C. L. 
Wright, of Augerville, is to find 
water at less depths on eastern 
slopes of hills than on western slopes, because of the eastward dip of 
the strata. There are numerous examples of both wells and springs, 




136 



UNDERGROUND WATER RESOURCES OF CONNECTICUT. 



however, which indicate that water flows up the slope after being fed 
into the bedding planes by joints. A well at Thompsonville, illus- 
trating movement of this type, is described on page 124. The water 
in this well is 25 feet higher than the water in Connecticut River, 
near by, which might otherwise be its source; the water-bearing bed 
does not outcrop farther east ; and there seems to be no source of sup- 
ply other than joints or faults. A well at the "old Talcott tower," 
near the edge of a 700-foot cliff, is believed to derive its meager supply 
from water moving up the 15° slope from the east. The hundreds of 
springs located along the western faces of low sandstone ridges that 
derive their water from a combination of joints and upward-sloping 
bedding planes may be illustrated by a spring on the estate of A. I. 
Ward, at Mount Carmel. (See fig. 22.) 




Figure 22.— Spring deriving its supply from joints and upward-sloping bedding planes. 
STATISTICAL TABLES. 

Yields of water at various depths in the rock below the covering of surface material. 
"Vol." = average yield in gallons per minute; "No." = number of records from which the average is taken.] 



Depth in feet. 


Vol. 


No. 


Depth in feet. 


Vol. 


No. 


0-30 


4.7 
14.8 
11.1 
17.7 
20.3 


3 
40 
44 
21 
29 


110-200 


27.6 
56.4 
40.7 
185.0 
40.0 


53 


30-50 .. 


200-300 


41 


50-70. . 


300-400 


7 


70-90. . . 


400-500. . 


6 


90-110... 


500-650 


5 









The foregoing table requires a little explanation, especially in 
regard to wells more than 400 feet in depth, where the recorded yield 
of 185 gallons a minute does not represent a true average. This esti- 
mate is the average of the yield of Hve wells in Hartford and one in 
South Manchester, in both of which places unusual conditions prevail. 
Moreover, the principal source of water of these wells is at a less 
depth than 400 feet, so that the same yields would have been obtained 
if drilling had stopped at 300 to 400 feet. Considered in this light, 
the data from wells 400 to 500 feet in depth indicate the presence of 



GROUND WATER IN TRIASSIC SANDSTONES AND TRAPS. 



137 



water in bedding planes down to 400 feet and should go to swell the 
average yield of wells 200 to 300 feet and 300 to 400 feet deep. 
The figures for wells more than 500 feet in depth likewise convey 
a wrong impression of the relation of yield to depth. The five wells 
included in the table report yields of 1, 2, 7, 75, and 125 gallons a 
minute. In all these wells the principal source of water is less than 
300 feet and in one well less than 50 feet below the surface. When 
these facts are taken into account the yield of wells more than 500 
feet in depth drops to an average of less than 10 gallons a minute. 

Average yields of wells in various locations. 



Location. 



Average yield 

(gallons per 

minute). 



Number of 
records. 



Valleys 
Hills... 
Slopes.. 
Plains.. 



64.3 
44.4 
17.7 

42.7 



Relation of level at which water stands in wells in various locations to surface of rock which 
marks bottom of overlying drift. a 



Location. 



Number. 



Percentage of 

wells with 

water level 

below rock 

surface. 



Percentage of 

wells with 

water level 

above rock 

surface. 



Percentage of 
wells with 
water level 
even with 

rock surface. 



Hills... 
Valleys 
Slopes. 
Plains. 



46.4 
12.5 
48.3 
31.3 



50.0 
87.5 
44.8 
64.7 



3.6 
0.0 



4.0 



a A summary of the results for all wells may be found on p. 133. 
Average depth from surface to water level in the well. 



Location. 


Depth to 

water. 


Number of 
records. 


Hills 


Feet. 
31.9 
16.9 
21.2 
19.9 


37 


Valleys 


10 


Slopes 


26 


Plains 


53 







Average depths, in feet, of surf ace material, of rock, and of the entire well for the records at 
hand, exclusive of wells more than 400 feet in depth and of wells known to be dry. 



Location. 


Average 

depth of 

surface 

material. 


Average 

depth in 

rock. 


Average 

total 

depth. 


Number of 
records. 


Valleys 


82.5 
39.4 
20.4 
39.3 


199.5 
73.9 
95.1 
93.8 


282.0 
113.3 
115.5 
133.1 


6 


Hills 


30 


Slopes 


22 


Plains 


50 







Note.— Average total depth of all these wells is 161 feet. 



CHAPTER VI. 

WATER IN THE GLACIAL DRIFT. 

INTRODUCTION. 

Exposed rock surfaces in Connecticut are confined largely to hill 
summits, cliffs, river valleys, and the shore line, and their combined 
area probably amounts to less than one-tenth of 1 per cent of the 
4,965 square miles constituting the area of the State. Where rock 
outcrops are absent, glacial drift forms the surface covering. The 
three classes of glacial material in which ground water occurs are 
till, stratified drift, and clay. 



CHARACTER AND WATER CAPACITY OF DRIFT. 

TILL. 

Till varies in texture from loosely compacted bowlders a few 
inches to several feet in diameter to a firm, dense, securely cemented 
mass of small rock fragments and clay, popularly called "hardpan." 
The composition of an average deposit of till is shown by the follow- 
ing mechanical analysis of the so-called Triassic stony loam from 
Bloomfield : 

Mechanical analysis of stony loam from Bloomfield. a 





Diameter of 
grains. 


Per cent. 


Gravel 


Millimeters. 
2 -1 
1 - .5 
.5 - .25 
. 25 - . 15 
.1 -.05 
.05 - .01 
.01 - .005 
.005- .0001 


2 


Coarse sand 


3.35 


Medium sand ■. 


8.60 


Fine sand 


31.25 


Very fine sand 


34.22 


Silt 


4.35 


Fine silt 


6.20 


Clay 


6.57 






Loss at 110° C 


1.36 


Loss on ignition 




2.03 









a Field Operations, Div. Soils, U. S. Dept. Agr., for 1899, p. 131. 

The soil represented by the foregoing analysis is the fine earth after 
coarse gravel and bowlders, varying in size from an inch to 7 or 8 feet 
138 



WATER IN THE GLACIAL DRIFT. 139 

in diameter, have been removed. The amount of gravel and unde- 
composed rock invariably exceeds 5 per cent, and may exceed 50 
per cent. 

The heterogeneous character of till makes it impossible to estimate 
its water-bearing capacity for any large area. The amount of clay 
present, the size, shape, and composition of the constituent bowlders, 
and the degree of compactness vary within wide limits, and therefore 
determinations of absorptive ratios apply only to the sample tested. 
Determinations of water capacity are made still more uncertain by 
the presence of irregular deposits of sand and gravel included within 
the till. The loosely compacted till has practically the capacity of 
conglomerate; the "hardpan" variety is almost as impervious as shale. 

A mass of till collected near Yale Field, New Haven, was found 
after five days of continuous drying to weigh 22 pounds. After soak- 
ing in water for one day and being allowed to drain the added water 
had increased its weight to 24.87 pounds, again of 2.87 pounds, which 
showed an absorption percentage of 11.55, or 3.46 quarts to a cubic 
foot of till. This is probably not far from the average capacity of 
till in Connecticut. 

STRATIFIED DRIFT. 

Stratified drift consists of sands and gravels with local clay bands 
and is composed of rounded waterworn fragments of the more 
resistant rocks, like granite, trap, and quartzite, together with an 
abundance of grains of quartz, mica, garnet, magnetite, etc. It 
owes its origin to streams, and especially to the water produced by 
the final melting of the continental ice sheet. As contrasted with 
till, stratified drift occurs in layers of various degrees of coarseness, 
depending on the velocity of the stream which deposited the debris. 

It must not be supposed that the stratified drift presents uniform 
conditions over large areas, for there are several types of the drift, 
each varying in texture, structure, and topographic appearance, in 
accordance with their method of formation. Flood-plain deposits 
and terraces contain numerous fine clayey layers. Delta deposits 
made in bodies of standing water exhibit strata of sand, gravel, and 
silt inclined at various angles, and the different sets of beds contain 
water in different amounts. a The grains composing sand and gravel 
come into contact with one another, but are so placed that there is 
much unoccupied space between them. Sand is practically sand- 
stone with cementing material removed and the water capacity 
proportionately enlarged. As a reservoir of ground water, stratified 
drift is therefore very important. Such material has been found to 
contain an amount of water equal to over 30 per cent of its volume. 

a Crosby, W. O., Water-Supply Paper U. S. Geol. Survey No. 145, 1905, pp. 177-178. 



140 



UNDERGKOUND WATER RESOURCES OF CONNECTICUT. 



The proportions of different sizes of grains in the average sand of 
the New Haven plain, are shown by samples from four localities 
analyzed by Freeman Ward, as follows : 

Size of grains in sand from New Haven plain. 



Size of grains. 



§ inch to a inch.. 
J inch to | inch . . 
| inch to Jjj inch . 
Less than T ^ inch 



0.9 

.7 

1.1 

97.3 



2.3 

2.7 

10.0 

85.0 



100.0 



100.0 



0.6 
1.6 
5.5 

92.3 



10(X0 



0.8 

1.6 

6.3 

91.3 



100.0 



Rain water is freely imbibed by stratified drift, and accordingly the 
surface dries very shortly after showers, and this material furnishes 
little water to streams. The water, however, stands close to the 
surface and the sands of plains and kames are thoroughly saturated. 
On the North Haven sand plain there is ' ' plenty of moisture a few 
inches below the surface, even in a protracted drought. a 

CLAY. 

The clays of Connecticut are largely the result of the deposition of 
fine material in lakes of glacial origin. They are accordingly strati- 
fied and usually contain layers of " strong clay" interbedded with 
sandy clay, quicksand, and sand of coarser textures. Clay consists 
of minute particles of kaolin, quartz, feldspar, mica, iron ores, etc., 
and when compacted under pressure these fragments are so nearly in 
contact as to give little pore space. However, the very small openings 
between the grains permit the access of much water, for each space 
acts as a capillary tube and the clay is expanded. The fine-grained 
clays, therefore, absorb and retain large amounts of water. That 
abundant water is present is indicated by the mud cracks in exposed 
clay surfaces and by the shrinkage which takes place on drying — 
an amount often over 10 per cent. The total amount of water in the 
brick clays of Connecticut is usually between 30 and 40 per cent. 
Most of the commercial clays of the State ' 'contain enough water to 
make them highly plastic, so that they can be tempered without addi- 
tion of more water." 6 



THE DRIFT AS A WATER RESERVOIR. 

The mantle of glacial drift spread over Connecticut is perhaps the 
most important single factor in the ground-water supply of the State, 
because it contains abundant water in itself and controls the supply 

a Britton, Bull. Torrey Bot. Club, vol. 30, 1903, pp. 571-620. 

b Loughlin, G. F., The clays and clay industries of Connecticut: Bull. Connecticut Geol. and Nat. Hist. 
Survey, No. 4, 1905, p. 63. 



WATER IN THE GLACIAL DRIFT. 



141 



of water to the underlying rocks. The bed rock exposed on the sum- 
mits and sides of hills is not in a position to absorb water. It is 
apparent that the greater part of any rainfall on such surfaces would 
run off immediately; in fact, a locality where even 2 per cent of the 
precipitation was absorbed by the rock would be exceptional. Even 
where there are wide-open cracks on the rock surface, the greater 
part of the water would run off before it could be absorbed by the 
few joints, which, not far below the surface, are so tight as to allow 
very slow passage to the water. 

On the other hand, where the rock is covered by glacial material 
the water does not run off rapidly but is absorbed by layers of porous 
sandy soil, from which in turn a considerable portion of the precipita- 
tion passes down into the rock fractures. Numerous shallow-dug 
wells indicate that the lower portion of the drift is in a saturated con- 
dition, being always ready to supply water to joints or faults or bed- 
ding planes below. The saturated belt in the surface material forms 
a constant reservoir, kept filled by uniform precipitation, from which 
water is delivered to the 
rocks to compensate for the 
amount removed by springs 
and wells. The sandy and 
gravelly portions of the drift 
are the most important res- 
ervoirs for supplying water 
to rock seams, for they carry 
a large quantity of water and 
allow ready passage; the 
clayey till, which may hold 
nearly as much water, allows very slow passage. The character of the 
overlying drift is, therefore, by its difference in permeability, largely 
determinative of the amount of water supplied to the underlying rock. 

The condition of the rock surface is another factor in the absorption 
of the water. At many localities the rock is marked by minor irregu- 
larities, due to a scooping out of the rock by glacial erosion (see fig. 
23), or to a dam of impervious glacial material. These small de- 
pressions in the rock serve as guiding channels to the circulation of 
ground water in the drift, and joints opening into these depressions 
have better opportunity for the collection of water than those inter- 
secting the rock surface at intermediate and higher points. Many 
depressed areas which have no outlet occur in the rock. In such 
basins the water collects and has no escape by seepage into rock 
joints, and evaporation is relatively unimportant where the drift has 
an appreciable thickness. 

Vertical joints are evidently more important than horizontal joints 
in giving opportunity for the entrance of subsurface water from the 




Figure 23. — Section of hilltop showing suitable catchment 
and. reservoir conditions for a water supply to the rock 
fractures. 



142 



UNDERGROUND WATER RESOURCES OF CONNECTICUT. 



drift. Owing to their parallelism to the rock surface many of the 
horizontal j oints pitch downward when they reach the ground surface 
and consequently do not offer good conditions for the entrance of 
water, although in exposures of bare rock the fractures lying at low 
angles tend to absorb more of the precipitation than the vertical 
joints. 

WATER BED AT CONTACT OF ROCK AND DRIFT. 

The glacial drift rests directly upon bed rock without any interven- 
ing soil or disintegrated material. (See fig. 24.) There is a sharply 

drawn line of contact be- 
tween the till, stratified 
drift, or clay and the 
gneiss, schist, sandstone, 
or other rock beneath. 
The contact forms a water 
bed, the supplies from 
which are larger and more 
permanent than those of 
any bedding plane in the 
Triassic sediments or set 
of joints in the crystalline 
rocks. As shown above, 
the drift is rilled with water, which percolates downward more rapidly 
than it can be imbibed by the rocks. The result is an accumulation 
of water at the rock surface which brings the drift to the point of 
saturation. In this way the layer immediately above the rock is sup- 
plied with water to 30 to 40 per cent of its volume, an amount equal 
to 2.24 to 2.99 gallons a cubic foot. Wells sunk to the contact of 
drift and rock show a large }deld. Three wells, owned by the Bradley 
& Hubbard Manufacturing Company, at Meriden, reach rock at 
depths of 203, 208, and 256 feet, and have a combined yield of 100 
gallons a minute. 

WELLS IN TILL AND STRATIFIED DRIFT. 

Probably three-fourths of all the wells in the State are shallow, 
open pits of large diameter, sunk in glacial material. (See fig. 25.) 




FlGUPE 24.- 



-Section showing common relation of rock surface 
to overlying drift. 





£S55§?^2^a^ 


>P$\>N 






/^tf/$\ ' 


5?§SS 


L^ 


\\/ c \/\ 
\ V > — /j 



Figure 25.- 



-Generalized section showing relation of rock to glacial drift. A, Layers of sand and gravel, 
partly saturated with water; B, bowlder clay; C, crystalline rock, 



WATER IN THE GLACIAL DRIFT. 



143 



Owing to the uniform rainfall, these wells yield sufficient water for 
domestic purposes, but the supply is uncertain and is subject to 
marked seasonal and annual variation. The data collected for this 
report, taken in connection with investigations made by the State 
board of health, indicate that such wells are not to be recommended 
either for large yields or for unqualified purity. 

WATER HORIZON. 

The principal water horizons in glacial drift are the porous sandy 
beds confined between beds of material more or less impervious. The. 
water-bearing layer may be 
sand or gravel, or even clay 
containing a small propor- 
tion of sand, and it may lie 
between layers of till and 
stratified drift, between dif- 
ferent members of a strati - 
fied-drift series, or between 
the till and bed rock. At 
Stafford Springs John Mc- 
Carty finds that wells in 
drift, which average about 
20 feet in depth, are sunk 
through a top covering of 
loam, followed by 2 to 10 
feet of sand and gravel, and 
then by a layer of hardpan 
5 to 20 feet in thickness. 
The water comes either from 
the sand above the hard- 
pan or, more commonly, 
from the contact between 
the hardpan and the under- 
lying rock. In many places 
the till acts as a confining 
bed to retain the water 
stored in both sand and 
gravel. In fact, the hard- 
pan variety of till exerts its chief influence as an impervious bed to 
limit the percolation of ground water. This relation is illustrated 
by the well of Mr. Coppus, at South Willington (see fig. 26), where the 
water enters in quantity at the junction of sand and underlying till. 
The most favorable water horizon, however, is in the drift, the zone 
lying immediately over bed rock, as explained on page 142, 







5>. Grave! 


: . : : : : : :: :": 5 an d :V.v;V:V::V. : 
" Fine 


: : ': : :':::'::::: S a n d '■'•;:;: ': "; " : '•}}. : : : :v. 

sand 
^J^9^iso n ■ ■ 

- o° f , o ~ <?-~ &:'■ 

.'•' -o d .'Till ;'»-• **•-*«». o °\ t 

" o °o° "f n • ° <? ' ■"' 


■.'■'<>•;■'.%■■ .A ' ■■=>• 
.<>■••*■-' ■ "■ c ' ■ ~ ■ 

■ o ^ o-o "/>'- 99. 

. < !i;:.q6':C)'.-.oV;o;v. 


Ml 



Figure 26.— Diagram of well at South Willington, showing 
water horizon at contact of till and stratified drift. 



144 UNDEEGEOUND WATEE EESOUECES OF CONNECTICUT. 

There is usually sufficient variation in the texture of the stratified 
drift to furnish pervious and impervious layers in contact. A slight 
variation in fineness of grain may be all that is necessary to concen- 
trate the water along one plane, but the most favorable relations 
exist where sand overlies clay. In the brick yards at Montowese, 
Berlin, and North Haven water is present in quantity along the up- 
per surface of the clay beds, and in other localities sandy layers 
between beds of clay furnish abundant water supplies. The whole 
North Haven sand plain is a good illustration of this relation. The 
area is underlain at a depth of 20 to 30 feet by beds of clay 5 to 20 
feet thick, on top of which lie sand and gravel. Water sinks so readily 
into the sand that vegetation is practically absent from this area, 
but wells sunk to the clay bed find abundant water, and where the 
strata are shown in sections, as along Quinnipiac River, there is a line 
of springs and seepages. In certain localities the bed of clay holds 
the water under hydrostatic pressure, and when this cover is pierced 
by a well the water rises nearly or quite to the surface. 

Wells sunk in till which does not contain sandy layers have no 
definite water horizon. In such wells the water is seen to form as a 
film and to drip from the surface, or to ooze out in small amounts 
around some of the larger bowlders. The circulation of water in 
such material is much retarded, and the wells are accordingly likely 
to vary much in yield. 

DEPTH AND YIELD. 

The average depth of the recorded wells in till is 24 feet, which is 
probably 5 feet too much, as an average for the State, because of the 
omission of a large proportion of shallow dug wells. The greatest 
depth reported is 151 feet and the least 7 feet. A few wells located 
at the contact of drift and bed rock flow at the surface. 

The average depth of 83 wells in stratified drift is 48.3 feet, a 
figure probably 10 feet in excess of an average made by including 
several thousand shallower wells sunk in this material. The deepest 
well in drift is 110 feet deep and the least depth recorded is 7 feet, 
but the tables do not include numerous wells with depths of less 
than 10 feet that are known to exist. 

These wells, both in till and stratified drift, probably procure all 
the water necessary for domestic purposes, for which they are largely 
used; by sinking to greater depths they could obtain much larger 
supplies. The average thickness of the drift cover over the sand- 
stones is 38.4 feet and over the crystalline rocks 36 feet, an average 
of about 37 feet for the State. It is readily seen that the wells in 
till, with an average depth of 24 feet, do not penetrate to great depths 
in this glacial material. The wells in stratified drift are sunk deeper 
and take more advantage of the opportunity offered to procure 
large supplies from a considerable thickness of drift. In case more 



WATER IN THE GLACIAL DRIFT. 



145 



water is desired, it is advisable to sink a well in drift to bed rock or a 
few feet into the fractured upper surface of the rock itself. These 
are the conditions, as explained above (p. 142) under which the largest 
yield of water may be obtained with a minimum depth of well. 

The number of wells recorded of various depths in the till and 
stratified drift is shown in the subjoined statement. 
Depths of wells in till and stratified drift. 





Number of wells. 


Depth, in feet. 


Number of wells. 


Depth, in feet. 


Till. 


Stratified 
drift. 


Till. 


Stratified 
drift. 


0-30 


84 
8 
1 


31 

21 

9 


70-90 


1 


7 


30-50 


90-110 


6 


50-70 


110-200 


2 


5 









QUALITY OF WATER. 

Till and stratified drift, alike, are composed of fragments of all 
sorts of rock, and it is therefore to be expected that the quality of 
the water should vary within wide limits, with reference to both 
depth and location, and that water from different depths and from 
different locations should be unlike in character. The waters of 
wells in till derived from sandstone and limestone are sure to con- 
tain compounds of calcium, magnesium, etc., making them hard, 
while wells sunk in drift composed of fragments of crystalline rocks 
are much more likely to yield soft water. Wells in till are more 
liable to have hard water than those in stratified drift, because the 
water circulates slowly and with difficulty in material of this sort 
and, accordingly, has an opportunity to take larger amounts of min- 
eral matter into solution. The tables of wells in till show 45 yield- 
ing hard water, 38 soft, and 11 medium in a total of 94 wells. In 
stratified drift 25 wells are reported to yield hard water, 30 soft, and 
4 medium out of a total of 59. 

Most wells in drift, especially if they are shallow and open and of 
large diameter, contain impurities. Wells of this character, espe- 
cially if they have been dug a number of years and are located near 
buildings, are so liable to contamination that an examination of the 
water should be made at short intervals. In thickly settled dis- 
tricts the water in shallow wells is often dangerous. Many wells 
near the beach sunk in stratified drift give brackish water, although 
a number of instances to the contrary may be cited. Wells in till 
are much less liable to contamination by salt water, and a number 
of such wells are located along the shore in close proximity to the 
Sound. Two wells at Saybrook Point are reported to contain fresh 
water except during dry seasons, when the water becomes low and 
brackish. 

463— irr 232—09 10 



146 UNDERGROUND WATER RESOURCES OF CONNECTICUT. 

WATER LEVEL. 

The wells in till have an average depth of 24 feet and those in 
stratified drift 48.3 feet so far as recorded. The average depth to 
water in these wells, however, is 10 feet for the till and 20.6 feet for 
the stratified drift. If the thousands of unrecorded wells in the State 
were added to the list the average distance of water from the sur- 
face would probably be still less. These figures indicate the freedom 
of circulation of water, especially in the stratified drift, for the princi- 
pal water horizon is at a depth of 35.5 feet and the average rise of 
water in the well is therefore 15 feet. Unlike the wells in sandstone 
and crystalline rocks, the wells in till and stratified drift are subject 
to great variation of water level, both annual and seasonal, and 
sometimes daily. 

The average variation of water level of wells in till recorded on 
pages 148-150 is 12 feet, sufficient to render many shallow wells 
valueless in dry seasons. Most of these wells have a regular annual 
period of maximum supply in late winter or spring, when they are 
full or overflowing. Single showers often raise the water level because 
of the added supply, but much more because of pressure on the air 
contained in the soil. Sudden rises of water in wells amounting to 
several feet are frequently reported, under circumstances where the 
rainfall could not have had time to enter the well through the drift 
and where the pressure of soil air was amply sufficient to account 
for the phenomenon. However, it is usually impossible to tell in 
any particular case, how much of the rise is due to infiltration and 
how much to the pressure applied to the air occupying the space 
between the grains. The wells of Sperry & Barnes, at New Haven, 
fluctuate in harmony with the level of water in the Sound, rising 
sometimes 10 inches in advance of the tide. The change in level is 
probably not due to the forcing of salt water toward the well, but 
rather to a squeezing of the fresh water from the pores of the sand, 
owing to the weight of the tons of water piled up on the shore. 

In stratified drift the fluctuation of the water level is not so marked, 
owing doubtless to the greater ease of circulation in the loose-textured 
sands and gravels. Sudden rises, however, due to air pressure, as 
explained above, are reported. 

The relation of rainfall to the fluctuation of water level in stratified 
drift is well shown by experiments conducted at the Yale Medical 
School, New Haven. a The well in which measurements were taken 
is sunk in sand at 146 York street, and the rain gage was located on 
the roof of the Medical School building on the adjacent lot, and read 
on the 15th of each month. As shown by the table below, the greatest 
depth of water at any time was 7.15 feet and the least 5.50 feet, 
showing a variation during the year of 1.65 feet. 

a Report Connecticut State Board of Health for 1889-90, p. 282. 



WATER IN THE GLACIAL DRIFT. 

Rainfall and variations in ground water at New Haven, 1889-90. 



147 



Month. 



Rainfall. 



Depth from 
surface to 

water. 



Depth of 
water. 



November, 
December. 
January... 
February., 

March 

April 

May 

June 

July 

August 

September 
October... 
November. 



Inches. 
5.16 
6.54 
.87 
3.96 
2.87 
7.13 
3.64 
4.36 
2.50 
5.23 
4.21 
6.21 
5.16 



Feet. 



57.84 



21.70 

22 

22.35 

21.90 

21.70 

21.90 

21.85 

22.70 

23 

23.35 

23.40 

23 



Feet. 



7.15 

6.85 

6.50 

6.95 

7.15 

6.95 

7 

6.15 

5.85 

5.50 

5.45 

5.85 



COST OF WELLS. 

Of 82 wells in stratified drift 28 are drilled, 22 are driven, and 32 
are dug. The average cost of 6-inch drilled wells is about $3.50 a 
foot; of 1^-inch driven wells, 70 cents a foot; and of 3-foot dug wells, 
$3.15 a foot. 

Wells in till have an average inside diameter of 3 feet and an 
outside diameter of 6 feet. They are usually lined with field stone 
and cost an average of $3.10 a foot. 

RECORDS OF WELLS IN TILL. 



The following table comprises the available records of Connecticut 
wells in till. 



148 



UNDERGROUND WATER RESOURCES OF CONNECTICUT. 



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WATER IN THE GLACIAL DRIFT. 



149 




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Woodbridg 
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Woodbury 



WATER IN THE GLACIAL DRIFT. 151 



NOTES. 

1. Passes through 3 feet of moist clay loam above 14 feet of hardpan. This is 
one of six dug wells varying from 16 to 28 feet in depth, and is stoned, jug shape. 

4. An excavated spring, the water being transported by a pipe with a 50-foot 
fall. 

5. Passed through hardpan for the entire depth. The water level varies greatly, 
the well being nearly dry in some seasons. A stream the size of a lead pencil was 
struck 6 feet from the top and another stream was encountered below a flat rock. 

6. In hardpan, with loam above. Water flows into the well from the northwest. 
10. Supply said to be practically unlimited and lowered with difficulty. Well is 

in sandy clay underlain by hardpan. 

21. Put down in 1900 through 14 feet of hardpan and obtained a strong flow from 
quicksand. 

27. Passed through 3 feet of soil and 22 feet of "clay hardpan" containing "stones 
as large as a water pail." No streams of water were encountered, the water oozing 
from the hardpan in drops. 

29. Blasted into rock 5 feet and occasionally becomes dry; 35 feet away is an 
unfailing well sunk 7 feet in till and containing soft water. 

33. Never failing, but varies, in amount of water with seasonal changes. Passes 
through 3 feet of loam and 15 feet of hardpan. 

39. Passed through 2 feet of topsoil, 8 feet of clay subsoil or hardpan, and 6 feet 
of sand and gravel. Water came in from several small veins (probably from sand 
and gravel). Water level lowers in dry seasons, but ordinarily rises within 8 feet of 
surface. 

43. Flows in wet seasons and occasionally runs dry at the same time as an adja- 
cent stream. The well is located on a sandy knoll, and may be in stratified drift. 

55. First 5 feet were soil and clay subsoil; first water struck at 9 feet, yielding 40 
barrels a day. Remaining 19 feet through hardpan containing and underlain by 
coarse gravel at the bottom, from which issued a large stream of water rising within 3 
feet of the surface. According to Rev. R. E. Turner, local artesian conditions prevail. 

63. Struck water at 13 feet below the surface, where rocks occurred in sand and 
water came in as a strong flow. Has never been dry. 

RECORDS OF WELLS IN STRATIFIED DRIFT. 

The available records of wells in stratified drift are summarized in 
the following table: 



152 



UNDERGROUND WATER RESOURCES OF CONNECTICUT. 



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WATER IN THE GLACIAL DRIFT. 



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156 UNDERGROUND WATER RESOURCES OP CONNECTICUT. 



NOTES. 

9. Dug in a springy spot, water being struck almost immediately, with a heavy 
flow &« the bottom. Level varies somewhat with seasonal changes, but even in dry 
seasons is high. 

20. Log shows coarse sand containing much water, beneath which is fine sand 
underlain by 6 inches of gravel, and clay at the bottom. 

21. First 12 feet through gravel, which overlies 50 feet of quicksand that plugged 
the pipe and prevented inflow. The water horizon is in gravel below the quicksand. 

47. Used for condensing ammonia in refrigerator. At 26 or 27 feet below surface is 
quicksand and below this clay. 

49. Located near together and used to supply water for baths and swimming pool. 

50. Driven in at sea level; water rises 10 inches in advance of the tide. The pipes, 
40 in number, pass through 7 feet of tide water, 25 feet of soft blue mud, 6 feet of hard 
blue clay, 3 feet of material resembling hardpan, and 2 feet of mixed coarse and fine 
gravel, which yields the water. A pipe has been sunk 300 feet from the surface, 
passing through quicksand all the way below the gravel to bed rock. 

64. Sunk through 5 feet of black and yellow loam and 16 feet of dark-colored hard- 
pan with cobblestones, reaching rock here at 25 feet below the surface. One-half 
mile farther north is a second well, 15 feet deep, which passes through soft loam and 
quicksand and yields an abundance of soft water. Immediately to the east are wells, 
10 to 12 feet deep, in gravelly soil. Toward the south the wells are in clay and hardpan. 

66. One of a gang of five driven wells (two 6-inch and three 3-inch) supplying the 
town of Ridgefield. Another 6-inch well is 75 feet deep but of small yield, probably 
because it passes nearly through the water-bearing gravel. 

70. Driven wells on gravel island in small lake. Temperature of water said to be 
48° to 52° from February 15 to July, and from July to February will rise to 58° to 62°. 

71. Said to have been drilled through hardpan, the water coming in several small 
veins. 

73. Passes through thin layers of loam and gravel and at 12 feet into "closely 
packed broken rock." 

76. Drilled 19 feet into rock, but the supply of water comes at the contact of the 
rock and the surface material. 

81, 82. Said to have passed through sand, gravel, and clay, deriving their water 
from clay. A complete record of a well in the same vicinity gives 15 feet solid clay; 
15 feet hardpan containing pebbles one-half inch to 3 inches in diameter; 41 feet 
gravelly dark soil; 29 feet bowlder material; 10 feet decomposed dry rock. 



CHAPTER VII. 

WATER SUPPLY OF TYPICAL AREAS. 

WARREN— A HIGHLAND TOWN. 

Warren is a typical highland town, with a population of 432, de- 
voted to agriculture and allied interests. It has an average eleva- 
tion of about 1,000 feet and an annual rainfall of about 50 inches. 
Mica schist (Berkshire) forms the bed rock in the western and south- 
eastern parts of the town; gray banded gneiss (Becket) occurs at 
Cornwall Center; and granite occupies the northeast corner of the 
town on both sides of the west branch of the Shepaug. Glacial till 
forms a mantle over most of the rock surface and constitutes the 
principal water-bearing formation. 

There are very few places in the town where abundant water is not 
found at a depth of less than 40 feet, and springs are numerous at 
low and high levels. In general, the farmers can choose between 
digging a shallow well and bringing water from a spring, as the cost 
of digging a 30-foot well is estimated to be the same as installing a 
pipe line 80 rods long. Mineral springs are not found in the town, 
and only one windmill is reported. The springs furnish soft water, 
the wells hard. 

The following detailed information regarding the water supply of 
Warren has been furnished by Myron A. Munson. The numbers 
refer to locations on the accompanying map (fig. 27). 

1. Spring sunk 4 feet, near the house; go for the water. 

2. Water for house and barn brought from spring 50 or 60 rods east; soft, and excel- 
lent; running since 1852. Also well 14 J feet deep, water 7 feet; poor, apparently 
surface water mainly. 

3. Water obtained from spring. 

4. Well 16 f feet deep; water 5 feet; good. 

5. Well 21 feet deep; water 8 J feet; excellent, "soft for a well, makes good suds." 

8. Well 15| feet deep; water 7 feet; rather hard; use rain water also. 

9. Well 19 feet deep; water very hard. There are two excellent springs at a dis- 
tance of 20 and 30 rods. 

10. Conditions not favorable for wells. 

13. Three wells on the place. The one now in use is less than 20 feet deep. W T ater 
was formerly soft; coal ashes were deposited in some near-by depression, since which 
the quality of the water has deteriorated. The well is unfailing, and the supply so 
copious that it is difficult to exhaust the well sufficiently to prepare it for cleaning. 
"It would supply water for a hundred cattle." There are two springs on the place 
with water having a temperature of 48°, 

157 



158 



UNDERGROUND WATER RESOURCES OF CONNECTICUT. 



14. Well about 12 feet deep; water is soft. 

17. Water conducted from a spring. 

18. Water brought from a spring on a lower level by means of a ram. 

19. Water brought to house from spring, which is about 25 feet above the doorstep 
and 15 rods distant; 2 feet deep; fails in dry season. A second spring, supplying 
water to barn, boils up through sand and never fails; water is conducted to south 
barn. A third spring, of constant flow, supplies milk house and horse trough. A 




WASHING! ON 



Figure 27. — Map of Warren, showing location of wells. 



fourth spring, unfailing, is used only as pasture supply. Across the swampy meadow 
to the west is another good spring. 

20. Rock ledge exposed; water formerly conducted from a spring. Conditions at 
the house are unfavorable for wells. 

21. Well 18 feet deep; water 5 J feet; not very hard; two springs across the road 
supply milk houses. 

22. Well 12 feet deep; water very hard. Spring at milk house across the road is 
declared to be "soft and sweet." 



WATER SUPPLY OF TYPICAL AREAS. 159 

23. Well 19£ feet deep; water hard; rain water also used. Spring at milk house 
consists of three streams, which gush up from sand. 

24. Obtains water from a spring in the field. 

25. Supply similar to No. 24. 

26. Has a "laundry spring " within 3 or 4 rods of the house; a better one 5 or 6 rods 
away; soft, and seldom failing. 

27. Well 12 feet deep; water hard; rain water also used. 

28. A good spring of soft water 5 or 6 rods distant from the house, "flowing as fast 
as can dip; " another colder spring is 4 rods farther away. 

29. Well 38 feet deep; water 22£ feet; hard, and unfailing. At 50 rods down the 
hill to the northeast is an ice pond into which five springs flow. An unsuccessful 
attempt was made to bring an unfailing spring from a distance of a quarter of a mile. 
A windmill was installed at the well a few years ago but was later discarded. 

30. Well 18 feet deep; water 9| feet. 

31. Well 16 feet deep; water 6| feet. Soft water is brought from a spring 30 rods 
distant. 

32. Brings .water in pails from an excellent spring of soft water at a distance of 8 
or 10 rods. 

33. This family obtains water from a good spring 30 rods distant. 

35. Water rather hard. 

36. Well 17| feet deep; water very hard, also contaminated. A new well about 12 
feet deep at a distance of 15 rods obtained good water. 

37. Well good; unfailing in driest times. 

39. Well 13 J feet deep; water hard, yet suitable for washing. 

41. Well 16£ feet deep; water said to be good. 

42. Well 23| feet deep; water a little hard. Used for all purposes, though a little 
way east and west of the house are two soft springs. Is the "best in town." Never 
known to fail when drought was most severe. 

43. Well 17 feet deep; water 7£ feet; a little hard; rain water (cistern) also used. 
Excellent spring 70 rods to the northeast in corner of the orchard ; another 150 rods to 
the southeast. Horse barn supplied from a well 10 feet deep, containing 6^ feet of 
water. "The springs about here are soft." 

44. Water carried from a spring near at hand, but at a lower level. 

45. Well 15 \ feet deep; water 6 feet; good. A spring in a swamp near at hand has 
been used. 

46. Well 7 or 8 rods west of house, 15^ feet deep; contains 7 \ feet of poor water. 
Water has been carried from the swamp named above (No. 45) into the cellar of this 
house, but the method worked poorly, and frequent repairing was necessary. 

47. Water conducted from a spring at a considerable distance. 

49. Water from spring at a distance of 40 rods. 

50. Well 5 feet deep; water hard; unfailing. 

51. Water brought from a spring sunk to produce a well of 12 feet depth; soft, good, 
and unfailing; has been used for fifty years. 

52. 53. Two of six houses supplied from a spring on the hills to the east. 

54. Unfavorable location for wells. Well measures 36^ feet, the "deepest in the 
town; " water 13 feet, but is " likely to become scant in the summer." 

56. Well 20^ feet deep; water has an iron taste. A well 13| feet deep across the 
road in a corner of the barnyard is said to contain good water. 

57. Well a few yards west of the house 16 \ feet deep; water very hard. A number 
of good springs on lower ground . 

58. Well 13^ feet deep spoiled by drainage from cesspool. There are six good 
springs, sweet and soft, on the place at no great distance, four of the six never failing. 
The house is supplied by two springs united, a quarter of a mile distant. A ram is 
employed. 



160 UNDEKGKOTJND WATEK RESOURCES OF CONNECTICUT. 

59. Well 17 feet deep; water 12J feet; "soft as a spring;" sometimes fails. 

61. Well 12 feet deep; water 6 feet; unfailing; soft, good for washing. Said on 
the spot to be the "best in town." 

62. Well 10 feet deep; water 5f feet, hard. Water is brought from a spring to this 
house and to the one across the road. 

65. Spring of cold water issuing from a beautiful grotto; water is of uniform tem- 
perature throughout the year. 

NORTH HAVEN — A LOWLAND TOWN. 

The conditions surrounding the occurrence and recovery of ground 
water in the central lowland are illustrated in the town of North 
Haven, a portion of which is shown on the accompanying map (fig. 
28). The area has an elevation of less than 100 feet and is underlain 
by sandstone, on top of which rest clays, sands, gravels, and till of 
glacial origin. Sand with large water capacity is the predominating 
surface formation. In the following descriptions the numbers refer 
to locations on the map: 

1. Well 30 feet deep; contains about 4 feet of water. In sand and gravel the entire 
distance. 

2. Well 30 feet deep; has 6 feet of water. In sand and gravel. 

3. Well 30 feet deep, in sand and gravel; has 4 feet of water, "not very good." 

4. A drilled well, 115 feet deep, all of the distance in sand and gravel. 

5. Well 20 feet deep; has 4 feet of water. In sand and gravel. 

6. One well 30 feet deep, with 5 feet of water; one 20 feet deep, with 6 feet of water; 
both in sand and gravel. There is also an excellent spring at this place, having a fall 
of 11 feet, which is sufficient to force water to all parts of the house. The ground 
water in the spring and in the shallow well appears to come from the northwest ; that 
in the other well comes from the northeast. 

7. Passes through sand, reaching rock at a depth of 20 feet. The water comes from 
just above the rock. The well is practically inexhaustible, three families using it all 
the time. 

8. A large supply of good water from a well sunk 17 feet into sand. Has 7 feet of 
water. 

9. Drilled in sandstone to a depth of 153 feet. Most of the water was reached at 
the 50-foot level. 

10. One well is 16 feet deep in red sandstone and near at hand is another well or 
spring 9 feet deep in which the water is seen to bubble up through the sand at the 
bottom. One hundred barrels of water have been pumped from this spring at one 
time without exhausting the supply. Both wells are very close to Quinnipiac River. 

11. Drilled well 45 feet deep; in rock for almost the entire distance. Gives an 
abundant supply of good water. 

12. Drilled in red sandstone to a depth of 126 feet, most of the water being reached 
at a depth of about 45 feet; yields a good supply of water. A spring also occurs in the 
back yard. 

13. Well 25 feet deep; walled with stone. After every freshet the sand pours in at 
the crevices so that it needs cleaning frequently. The water is excellent and abundant . 

14. Well 15 feet deep; contains 5 feet of water. It does not fail, and the water is 
soft and good. 

15. Well 16 feet deep; holds 8 feet of water. The water is very good, but fails in dry 
seasons. Spring 300 yards to the northeast gives an abundance of water for house use 
and is high enough to send water into all the rooms of the second story by gravity, 
There is also a spring at the barn. 



WATER SUPPLY OF TYPICAL AREAS. 



161 



16. Constant spring of good water. 

17. Said to be about 20 feet deep. 

18. Well 17 feet deep. The first few feet are in sand and the remainder in red 
sandstone, with a sharp easterly dip. The water occurs in the rock and varies but 
little with the seasons. 

19. Well 22 feet deep; has about 4 feet of soft water. 

20. Well 30 feet deep, the last 18 feet in red sandstone. The water found in the 
rock is soft and plentiful. 

21. Well 30 feet deep, in sand and gravel. About 5 feet of soft water stands con- 
stantly in the well. 




Vz Mile 



Figure 28.— Map of North Haven, showing location of wells. 



22. Well sunk 35 feet in sand. Water is plentiful and not very hard. 

23. Two wells; one at barn 25 feet deep with 3 feet of water; one at house 30 feet 
deep with 5 feet of water. Neither well runs dry. 

24. Well 30 feet deep; has 5 feet of water. The first 25 feet are said to be in hardpan 
and the remainder in sand. Abundant water was found in the sand. 

25. Well 30 feet deep. The first 25 feet are in the hardpan, then comes 2 inches 
of sand in which the water is found, and then about 4 feet more of hardpan. The 
water is plentiful, varies from 3 to 11 feet in depth, and is soft enough, to be used con- 
tinually for a laundry. 

463— irr 232—09 11 



162 TJNDEKGROTJND WATER RESOURCES OF CONNECTICUT. 

26. Drilled well 128 feet deep. It is reported that the first 84 feet are in sand and 
hard gravel and the last 44 feet in hardpan. 

27. Drilled well 140 feet deep; derives water at depth of 100 feet, near contact of 
rock and till. Water is hard, rises within 25 feet of the surface, and does not vary in 
amount with seasons. 

28. Well dug in hardpan to a depth of 44 feet. In the spring it sometimes contains 
as much as 15 feet of water. ' ' This water will rust a tin in one night. ' ' 

29. A very old well, dug and walled with brick; 45 feet deep; amount of water 
varies from 5 to 15 feet. 

30. Dug well, 29 feet deep; contains 4 feet of water. 

31. Dug to a depth of 45 feet in course gravel. Became dry during one season. 

32. Dug to a depth of 12 feet in sand and gravel. It was dry once, but only for a 
short time. Ordinarily about 2 feet of water stands in the well. 

33. Family gets water from a spring which issues at the top of a layer of clay. 

34. Well 15 feet deep; has 2 feet of water. Walled with brick, but abandoned on 
account of surface contamination. 

35. Drilled well, 195 feet deep; yields 8 or 10 gallons a minute. The first few feet 
are in sand, then comes about 50 feet of clay underlain by red sandstone. There are 
several recently drilled wells in this neighborhood, and their use has been followed 
by a great decrease in the number of cases of malaria. 

36. Water for drinking purposes is brought from a spring which emerges at the con- 
tact of sand and clay. 

37. Dug through sand and strikes a clay stratum at 13 feet. 

38. Dug to a depth of 15 feet 6 inches, where it strikes sandstone; contains 7 feet of 
water and does not fail. 

39. Dug in rock to a depth of 15 feet; contains about 7 feet of water. 

40. Well on the hill is dug to a depth of "about 50 feet," the last 40 feet being in 
sandstone. At this same locality a shallow rock spring with insufficient water was 
converted into a satisfactory supply by drilling 10 feet into the rock. 

41. Dug well 7 feet deep, the last 4 feet in red sandstone. The ground water is seen 
to come from the northwest. 

42. Well at barn dug to a depth of 13 feet 6 inches, in sand and gravel; yields 
hard water. Well at house, in the cellar, is about 15 feet deep; passes through gravel 
to hardpan, where an abundant supply of soft water is procured. 

43. Conditions same as at No. 42. 

44. Drilled well in sandstone with a depth of "over 100 feet." 

VICINITY OF BRANFORD POINT— A COAST REGION. 

The region about Branford Point is fairly typical of the coast 
resorts along the Connecticut shore. It includes rocky knolls, 
stretches of sand flats and beaches, and expanses of marsh land. 
The bed rock of this area is gneiss, much broken by joints and 
planes of parting. The soil cover is till and beach sands. The 
insufficiency of supply and the danger of contamination by salt 
water have made it advisable to conduct water by pipe line from 
Branford River and to make this the chief supply. Two small 
springs are reported from this area. 

The following descriptions accompanying the map (fig. 29) give 
detailed information regarding conditions which are typical of the 
water at Connecticut resorts. 

1. Well 25 feet deep; contains about 5 feet of water, which is soft enough to make 
good suds. 



WATER SUPPLY OF TYPICAL AREAS. 



163 



2. Weil has constant supply, medium in softness. It is 23 feet deep and con- 
tains 5 feet of water. 

3. Well 24 feet deep; contains about 4 feet of water of medium softness. 

4. Same depth and character as No. 3. 

5. Well 27 feet deep; contains 3 feet of water. 

6. One of the wells at this place is situated 5 feet from the edge of a salt marsh, 
but has never been known to become brackish. It is a driven well to a depth of 14 
feet and contains 4 feet of water. The other well is sunk through glacial till, is 22 
feet deep, and derives water from the contact of rock and till. 




VzMile 



Figure 29. — Map of vicinity of Branford Point, showing location of wells. 



7. A permanent well with water of medium softness; 32 feet deep; contains 4 feet 
of water. 

8. Water said to be harder than in the other wells of the vicinity. The depth of 
the well is 33 feet and the water stands at 29 feet. 

9. Well of hard water, 33 feet deep. 

10. Dug to a depth of 25 feet; contains 4 feet of hard water. 

11. Well 25 feet deep; has 4 feet of hard water; has never been known to fail. 

12. Well 25 feet deep; has 4 feet of water. 

13. Although situated very near the salt marsh and the tidal river, this well con- 
tains good water. It is 26 feet deep and has 3 feet of water. It has never failed. 



164 UNDERGROUND WATEK RESOURCES OF CONNECTICUT. 

14. This place is supplied by a well driven 5 feet below the cellar floor. Fresh 
water enters "like a spring" at the edge of the marsh. 

15. This factory is located mostly on "made land" recovered from a salt meadow. 
Wells were brackish and were accordingly abandoned. 

16. Well 12 feet deep; contains 1 foot 6 inches of water. Water became brackish 
and has been discarded in favor of city water. 

17. Well 23 feet deep; contains a constant supply of about 3 feet of hard water. 

18. Well 25 feet deep; contains 2 feet of hard water. 

19. Well 25 feet deep; has 3 feet of soft water; yield regular. 

20. Well 22 feet deep; has 3 feet of hard water. 

21. Well at barn 15 feet deep; contains about 4 feet of water. City water used at 
house. 

22. Well sunk in rock much broken by joints which permit access of salt water. 

23. Well 25 feet deep; contains 2 feet 6 inches of water which is little affected by 
dry weather. Water is claimed to be soft and palatable. 

24. Rain water is used because wells give brackish water. 

25. Two driven wells in house, each 24 feet deep. One of these wells has yielded 
a good supply of soft water for twenty years. 

26. On a narrow neck of land between two salt marshes and not over 20 feet from 
one of them; 16 feet deep; contains 3 feet of hard water. 

27. Well 17 feet deep; contains 3 feet of water, which is wholesome but a little 
hard. 

28. Well 23 feet deep; contains a constant supply of hard water. 

29. Water is medium in softness. Well 25 feet deep, with 3 feet of water, and does 
not fail. 

30. Well 22 feet deep; contains 2 feet of water of an unsatisfactory quality. 

31. Well 24 feet deep; contains 3 feet of water of medium softness. 

32. Well 25 feet deep; contains 4 feet of soft, wholesome water. 

33. Well 16 feet deep, with 5 feet of water of good quality. 



CHAPTER VIII. 
CHARACTER OF GROUND WATER OF CONNECTICUT. 

INTRODUCTION. 

• 

Pure water, as a compound of hydrogen and oxygen, is not known 
in nature. Descending rains take from the atmosphere considerable 
of its impurities and carry them to the ground; carbonic acid, sul- 
phates and nitrates, especially near cities where coal is used for fuel, 
sodium chloride in the vicinity of the sea, and atmospheric dust con- 
tribute to the rainfall. Of the common gases rain water contains 
about 25 cubic centimeters per cubic meter, consisting of nitrogen 
about 64 per cent, oxygen 34 per cent, and carbonic acid 2 per cent. 
With the exception of chlorine, however, all the impurities of the air 
may be disregarded in the study of ground water. 

After water enters the soil, it gathers materials from rocks and 
from decomposing organic matter. Sodium and potassium are taken 
from rocks containing feldspars. Calcium and magnesium are ex- 
tracted from limestones and in less degree from rocks of other types. 
The minerals taken up by water in its subterranean course are chiefly 
silica, iron, aluminum, calcium, magnesium, sodium, potassium, 
chlorine, organic acids of uncertain composition, and the carbonate, 
bicarbonate, sulphate, and nitrate radicles. Barium, strontium, 
lithium, and other elements occur less commonly in appreciable 
quantity. Free carbonic acid gas is an ordinary ingredient of natural 
water, and oxygen, hydrogen, nitrogen, Irydrogen sulphide, and 
hydrogen phosphide in solution are occasionally encountered. 

As the value of water for any given purpose is determined by its 

composition, chemical study of surface and ground waters becomes a 

matter of great practical importance. The composition of ground 

water in Connecticut is of prime interest, because only the larger 

cities within the State receive their water supply from brooks or 

lakes. Of the 168 towns in the State 140 depend entirely on wells 

and local springs for their water supplies, and it is estimated that 40 

per cent of the population obtain water for domestic purposes from 

more than 90,000 wells and springs. 

165 



166 UNDERGROUND WATER RESOURCES OF CONNECTICUT. 

COMPOSITION. 
DETERMINING CHARACTERS. 

The composition of the ground waters within the State is deter- 
mined by the character of rock from which they are drawn. Shallow 
wells and springs in glacial drift contain substances leached from the 
upper soil and include nominal amounts of chlorine, sulphates, car- 
bonates, nitrates, silica, calcium, magnesium, potassium, and sodium, 
with iron and aluminum in small amount, and a relative absence of 
organic matter. The deeper wells in the drift contain the same sub- 
stances, but larger amounts of iron and less nitrates. Waters from 
glacial till and from rock are characterized by their relatively high 
content of calcium, magnesium, and sulphates. This is particularly 
true of water from sandstone and closely packed till or hardpan. 

HARD AND SOFT WATERS. 

As water takes up chemical compounds during its percolation 
through the ground, it often becomes what is commonly known as 
"hard" water, the term indicating its ability to form insoluble cal- 
cium and magnesium soaps when used for washing purposes. The 
greater proportion of the mineral constituents dissolved in shallow 
ground waters is obtained near the surface in what is known as the 
belt of weathering. This is the unsaturated zone between the ground 
surface and the level of the water table. The mineral constituents 
of this belt are relatively insoluble in their natural state, but they 
are continually undergoing oxidation, hydration, and carbonation, 
which result in the formation of compounds soluble in water. In 
the upper portion of the soil there is a large amount of organic 
matter which is oxidized through natural decay to carbonic and 
other acids. These acids, dissolved in water, attack the rocks and 
increase the mineralization of the underground supply. Calcium and 
magnesium in equilibrium with the bicarbonate radicle in water 
constitute temporary hardness, so-called because the minerals may 
be removed by boiling the water. If, however, the sulphate rather 
than the bicarbonate radicle is present the water is said to be per- 
manently hard because boiling will not remove the dissolved min- 
erals. The amount of calcium and magnesium present determine 
the relative hardness of water, and the proportions of the bicar- 
bonate and sulphate radicles determine its character. The oxidation 
of iron sulphide is probably a source of sulphuric acid, which may 
decompose rocks with which it comes into contact. Among the 
most common constituents of crystalline rocks are silicates of iron, 
aluminum, calcium, and magnesium. These silicates in themselves 
are practically insoluble in water at ordinary temperatures, but in 



CHARACTER OF GROUND WATER. 167 

the presence of waters containing carbon dioxide they are subjected 
to chemical changes and are carried away in solution. 

There are many other methods by which water obtains mineral 
matter in solution, but those cited above are sufficient to illustrate 
the processes. It has been estimated b} r Reade° that for the entire 
earth there is removed annually in solution 96 tons of material per 
square mile, consisting of calcium carbonate, 50 tons; calcium sul- 
phate, 20 tons; sodium chloride, 8 tons; silica, 7 tons; alkaline car- 
bonates and sulphates, 6 tons; magnesium carbonate, 4 tons; oxide 
of iron, 1 ton. 

MATERIAL TAKEN INTO SOLUTION. 

Although there are many factors determining the character and 
the amount of the materials taken into solution by underground 
water, only two need be considered in this discussion. They are 
the character of the material traversed by the water, and the dis- 
tance which the water has traveled underground. The waters of the 
glacial drift exhibit great variability of composition and are almost 
equally divided between hard and soft waters. In general the waters 
from the finely divided clay till are hard and those from the sand 
and gravel deposits are soft, owing to the character of the material. 
The sand and gravel deposits are composed largely of coarse grains 
of quartzose materials, which are dissolved with great difficulty by 
water, but the till is made up in part of masses of finely divided 
heterogeneous material which not only offer a more varied assort- 
ment to be acted on by waters but also give greater opportunity for 
solution owing to their fineness of grain. The deep-well waters of 
the sandstone are much harder than those of the crystalline rocks. 
In the latter the crevices afford the only passage for the water, and 
consequently the solvent action of the water is largely confined to 
the immediate walls of the crevices. In sandstone, however, the 
water traverses the entire rock, passing not only through the seams 
but also through the small pores between the grains, and thus has 
a vastly greater surface for action. Many of the sandstones of Con- 
necticut are arkoses containing as great variety of mineral constitu- 
ents as the original crystalline rocks. 

In regard to the distance that the water travels, it is manifest 
that the longer and the slower the passage the greater opportunity 
there will be for solution. Increase of heat and pressure increases 
the solvent power of water; the waters which have penetrated deeply 
and have been subjected to great heat and pressure often have a 
larger proportion of dissolved minerals than those at shallow depths. 

a Reade, T. Mellard, Chemical denudation in relation to geological time. 



168 UNDERGROUND WATER RESOURCES OF CONNECTICUT. 

Analyses of waters from 13 wells in crystalline rock give an average 
of 132 parts per million of total solids. Analyses of 18 well waters 
derived from Triassic sandstone areas average 655 parts per million 
of solid matter. Exclusive of three well waters that contain over 
1,000 parts of solid matter, the average for 15 well waters from sand- 
stone is 377 parts per million. Five well waters from glacial drift 
average 263 parts of mineral matter. The analyses of 25 spring 
waters give an average of 73.5 parts of total solids. It is impossible 
to state from the available data whether springs from one source con- 
tain more mineral matter than those from a different source. The 
information at hand gives no indication of any definite increase of 
mineral matter with increase in depth of the well, and though there 
might be such increase in very deep wells, it seems that within the 
ordinary limits of well depth in Connecticut — between 100 and 500 
feet— the relation of mineral content to depth has no practical 
bearing. 

NORMAL DISTRIBUTION OF CHLORINE. 

Chlorine, which is a constituent of common salt, is present in all 
natural waters and comes from salt deposits within the earth or from 
salt-laden spray from the ocean. In Connecticut there are no de- 
posits of salt or other chlorine compounds from which waters might 
derive appreciable amounts of chlorine, but this substance is present 
in them in considerable quantity and the proportion of it in ground 
water decreases regularly with increase of distance from the coast. 
The obvious inference is that the natural waters obtain their chlorine 
from the minute particles of sea water that are blown inland by the 
winds. The amount of chlorine in normal waters of Connecticut 
has been determined for different parts of the State, a and a map pre- 
pared under the direction of Prof. H. E. Smith, of the Yale Medical 
School, indicates the normal distribution of chlorine by means of 
isochlors or lines defining the areas within which the waters in their 
natural state contain certain definite amounts of chlorine. (See 
PI. Y.) The value of knowledge regarding the normal distribution of 
chlorine is that it affords a ready basis for testing the purity of both 
surface and subterranean waters. Salt is present in all animal 
dejecta and eventually finds its way to the water courses, both above 
and below ground; consequently if a water contains more chlorine 
than the normal amount for the area in which it occurs, the presence 
of sewage or other contaminating matter may be suspected. Excess 
chlorine in wells immediately adjacent to salt water is not necessarily 
an indication of sewage contamination, but usually of the admixture 
of sea water. 

a Rept. Connecticut State Board of Health for 1902, pp. 227-242. 



U. S. GEOLOGICAL SURVEY WATER-SUPPLY PAPEft 232 PLATE" V 




F 

v ne is expressed in parts per million 

chlorine 

tad chlorine in waters which are 
(1 or nearly so 

d waters 



4f 




MAP OF CONNECTICUT, SHOWING DISTRIBUTION OF CHLORINE. 



CHARACTER OF GROUND WATER. 169 

USES OF WATER. 
WATER FOR DOMESTIC PURPOSES. 

The uses to which underground water is ordinarily put in Con- 
necticut are relatively few in number. Owing to the ease with which 
large amounts of soft water are obtained, city supplies are usually 
taken from ponded reservoirs fed by surface drainage and by springs. 
For private residences and manufactories outside of cities, however, 
wells constitute the chief source of water supply for general purposes, 
and even in cities some manufacturing concerns find it expedient 
to use well water. 

The three main purposes for which well and spring waters are used 
are for domestic supply, as in cooking, drinking, and washing, for 
boilers, and for coolers. A reasonably soft water is desirable for all 
these purposes and is particularly necessary in the case of boiler 
water, because hard waters form a scale in boilers, causing a heavy 
expense for additional fuel, cleaning of flues, extra firings, and boiler 
repairs. Soft water is preferable for general domestic use, though it 
is not so palatable as hard water. In breweries, distilleries, and 
other manufacturing establishments where a supply of cool water 
effects a great saving in artificial refrigeration, well waters are 
economical. 

WATER FOR BOILERS. 

Most of the large manufacturing establishments in Connecticut 
are on the banks of the more important streams, where abundant 
water for boilers may ordinarily be obtained from the heavy sand 
and gravel deposits that fill the major valleys. Such supplies are 
reasonably soft and cold and are satisfactory for cooling and boiler 
purposes, although frequently unsafe for drinking owing to surface 
contamination. Wells penetrating a considerable distance into 
the rock are preferable as sources of drinking water. Water from 
wells in the crystalline areas is usually soft enough for boiler use, but 
that in the sandstone areas is likely to be hard and is frequently dis- 
astrous to boilers. A study of Connecticut waters with regard to their 
availability for steaming purposes has been made by George H. 
Seyms, chemist of the Hartford Steam Boiler Inspection and Insur- 
ance Company, who has kindly allowed free use of his valuable data. 
Mr. Seyms has classified Connecticut waters in regard to their use in 
boilers, taking into account the average proportion of the different 
constituents in the normal waters of the State and assuming that 
one-half of the total solids is incrusting matter. Water containing 
less than 250 parts per million of solid matter is pronounced good. 
Water containing between 250 and 500 parts of solid matter is fair 
for boiler use, but if the amount exceeds 500 parts the water is unfit 



170 UNDERGROUND WATER RESOURCES OF CONNECTICUT. 

for general boiler purposes. In making this estimate the fact has 
been taken into account that in most parts of the State supplies of 
soft surface waters may be obtained at reasonable rates. Increased 
hardness means increased cost of maintenance and where hard 
waters are used for boilers, as in the Western States, it is only because 
supplies of soft water are not available. The water supplies of Con- 
necticut are recommended by Mr. Seyms for boiler purposes in the 
following order: (1) River waters (where uncontaminated by fac- 
tory wastes); (2) ponded reservoirs; (3) small streams (as compared 
with rivers) ; (4) springs and shallow wells 30 to 50 feet deep; (5) deep 
wells. Wells in sandstone are less suitable as a source of water for 
boiler use than those in crystalline rocks. 

CONTAMINATION. 

INTRODUCTION. 

That the ground water of Connecticut is liable to contamination 
and needs careful and frequent examination is well shown by the 
analyses of tainted waters made by the state board of health and by 
the typhoid epidemics which have occurred within the State. In 
1893 the health officers of 119 towns reported on the condition of 
water supply, a and pronounced the water of only 82 towns unquali- 
fiedly good. In 1898 analyses were made of water from 247 wells on 
the premises of public schools in the State; only half of them were 
free from suspicion of dangerous contamination and many were 
highly polluted. 6 In 1899 only three out of 14 suspected wells ex- 
amined were declared safe. c In 1902 the water supplies of 101 hotels 
and restaurants and summer resorts were inspected, and only 20 out 
of 33 samples taken from springs, wells, and cisterns were considered 
safe. d 

Sixty cases of tj^phoid, probably caused by water from a well 25 
feet from a house, occurred in 1882 at Portland. 6 The drainage 
from a vault entering the quicksand caused typhoid at Guilford 
during the same year./ Water from a well in Middletown gave 
typhoid to an entire family in 1884.^ The analyses of water from 
three wells at Madison in 1885 revealed the source of pollution which 
caused 14 cases of fever. n Contaminated water at Money Island 
caused 21 cases of typhoid in 1891.*' The epidemic at Stafford in 1894 
was traced to a polluted well.' The great epidemic at Stamford in 
1895, in which 386 people were afflicted, was caused by milk delivered 
in cans which had been washed in well water infected by drainage 
from vaults.* 

a Ann. Rept. Connecticut State Board of d Idem, 1902, pp. 223-226. h Idem, 1885, pp. 342-344. 

Health, 1893, p. 110. « Idem, 1882, p. 140. * Idem, 1891, pp. 205-213. 

b Idem, 1898, pp. 279, 280. / Idem, 1882, p. 144. 3 Idem, 1894, pp. 232-238. 

c Idem, 1899, p. 21. g Idem, 1884, pp. 79-81. * Idem, 1895, p. 161. 



CHARACTER OF GROUND WATER. 171 

Typhoid at Eastern in 1895 was t raced to a well adjoining a pig pen. 05 
Thirty cases of typhoid in Glastonbury in 1895 were caused by a con- 
taminated well at Hopewell. 6 An investigation of the typhoid at 
Ridgefield in 1901 showed that the entire ground water of an area 
covering several blocks had been contaminated by sewage. c The 
typhoid epidemic, 84 cases in all, at Bristol in 1903 was due to 
infected water from a farm well and spring. d Several less conspicu- 
ous occurrences of typhoid are likewise directly traceable to contami- 
nated ground water. 

"It is now universally recognized that the degree of prevalence of 
typhoid fever in a given community is a reliable measure of the 
extent to which sewage is an ingredient in its drinking water. The 
prevalence of typhoid in cities is a true index of the quality of the water 
supplies." e 

The annual death rate from typhoid in Connecticut has been 
steadily decreasing, and this satisfactory record is due largely to the 
increased attention paid to the character of water supplies. 

CONTAMINATION BY SEWAGE. 

Sewage is the most widespread source of contamination of water 
in springs and wells. Drainage from vaults, cesspools, broken sew- 
ers, slops thrown on the ground, pig pens, and other sources of filth 
passes readily into the ground water and is the common vehicle for 
substances dangerous to health. 

LOCATION OF WELLS. 

The location of a well is the most important consideration in 
obtaining pure water. The well should be placed at a considerable 
distance from any known source of contamination, on ground of 
relatively high elevation, and should be surrounded by an open, clear 
space, preferably grass covered. The direction of the flow of ground 
water for the area should be determined, if possible. Many wells in 
Connecticut are located in utter disregard of the simplest principles 
governing the movement of underground water. Instances might be 
cited where cesspools and other waste reservoirs are within 25 feet of 
wells used for domestic supply. For some wells the worst possible 
locations seem to have been selected. The writer has noted between 
40 and 50 wells located on slopes below cesspools, in such manner 
that the contaminated waters, either in drift or in rock, are carried 
with certainty into the wells. It is not the depth but the location of 
a well which usually determines its purity, and a 20-foot well located 
with care may be much safer than a 100-foot well sunk without 

a Ann. Rept. Connecticut State Board of Health, 1895, p. 90. d Idem, 1903, p. 88. 

b Idem, 1895, p. 99. « Idem, 1899, p. 21. 

cldem, 1901, pp. 301-305. 



172 UNDERGROUND WATER RESOURCES OF CONNECTICUT. 

regard to surrounding conditions. A good illustration of this is the 
well on the New Haven Green, a shallow well in the heart of the 
largest city of Connecticut. The quality of the water is good, because 
the surface about it is protected on the south and east by pavements 
and because its water is received from the Green, a grass plot 16 
acres in extent, kept clean by the city authorities. 

There is a general impression that soil will filter the impurities from 
water within a few feet of its source and that contamination of wells 
is due chiefly to material falling in at the top. No more dangerous 
error could be propagated. The purifying power of a soil is limited 
and it may easily be overburdened. In fact, the value of any soil 
filtration is uncertain, and it is impossible to state that water will be 
purified by passing through any amount of soil. The uncertainty is 
greatly increased by the existence of more or less open channels, 
which offer rapid passage to underground water with little filtration. 

DEPTH AND CONSTRUCTION OF WELLS. 

Shallow wells are much more likely to become contaminated than 
deep wells, and as probably 80 per cent of all wells within the State are 
less than 25 feet in depth, the importance of care in their maintenance 
is evident. There is in Connecticut, particularly in the rural districts, 
a strong prejudice in favor of the shallow, open well and a belief that 
clear, sparkling, palatable water is sure to be pure. The danger in 
these beliefs is very real, for certain parts of sewage tend to give 
water a sparkle which is highly appreciated by those unacquainted 
with its character. Drilled or bored wells have many advantages 
over shallow dug wells. There is less chance for foreign substances 
to drop into the well, and it is possible to shut off all surface and 
seepage water. The "old oaken bucket" has sentimental advan- 
tages, but iron pipes and creaking windmills are much better sym- 
bols of the purity of drinking water. 

CONTAMINATION IN DIFFERENT ROCK TYPES. 

Contamination of water in shallow drift wells has been the cause 
of many typhoid epidemics in Connecticut, as at Bristol, Easton, 
Glastonbury, Guilford, Madison, Middletown, Portland, Kiclgefield, 
Stamford, and Stafford. The water supply at Camp Coffin was found 
to be contaminated in 1896 by water that collected in a pool used for 
washing clothes and reached the well by sinking through a consider- 
able depth of sand and gravel. In 1903 the Chamber of Commerce 
of New Haven made an investigation of the local water supply, which 
led to the recommendation that all wells within the city should be 
abandoned as sources of water for domestic uses. The wells examined 
are mostly in till or stratified drift, range in depth from 20 to 220 feet, 



CHARACTER OF GROUND WATER. 173 

and are located in all sections of the city. Six samples were taken 
from wells 20 to 30 feet deep, eight from wells 30 to 50 feet deep, 
five from wells 50 to 100 feet deep, and nine from wells over 100 feet 
deep. The committee reported that, with the exception of a few 
samples from the outskirts of the city, all showed evidence of a past 
contamination in a more or less marked degree. In Hartford, 
Waterbury, and other cities analyses of water derived from sand and 
gravel deposits commonly indicate considerable sewage contamina- 
tion, although the water is obtained at points 30 to 50 feet below the 
surface. In fact, it is doubtful if any well is safe in a thickly settled 
community. 

Spring water may likewise become contaminated by sewage-laden 
ground water, as illustrated at Forestville and South Norwalk during 
the typhoid epidemics of 1900. a 

Though drilled wells are much less subject to sewage and drainage 
contamination than shallow-dug wells of large diameter, equal care 
should be taken in their location. A number of deep wells have been 
drilled in the low central portion of Hartford, and many of them show 
heavy contamination in waters supposed to be derived more than 200 
feet below the surface. This is a portion of the city which received 
for years a large amount of drainage, so that whatever water enters 
the rock through the soil carries with it considerable contaminating 
material. Some of this water finds a ready passage through more or 
less open joints and enters the wells. The contamination of many 
such wells results from imperfect casing and the consequent entrance 
of water from the surface. There is little doubt that in certain wells 
imperfect joints allow shallow waters to enter the well at the contact 
of the rock and the drift. Such poor construction may be due to 
carelessness, or to intention, owing to the desire of the driller to 
obtain a sufficient supply of water. The entrance of any water at the 
junction of the casing and the rock may be detected if a mirror is 
used to reflect light into the well. 

That contaminated water may circulate through considerable dis- 
tances of sandstone is shown by the experience of Hartford, already 
described. At the Wallingford Sanitarium a well was contaminated 
by gasoline which flowed through the bedding planes of rock for a dis- 
tance of 225 feet at a depth of 8 feet below the surface. Many simi- 
lar cases might be cited. 

Even wells sunk in granite and other crystalline rock are not free 
from contamination by circulating water. The typhoid epidemic at 
Sachem Head was caused by drinking water from a well blasted in 
rock to a depth of 16 feet. It was shown that the contaminated 
water passed through joints for a distance of 6 feet. At Millstone 

a Ann. Kept. Connecticut State Board of Health, 1900, pp. 274-285, 286-289. 



174 



UNDERGROUND WATER RESOURCES OF CONNECTICUT. 



Point brackish water was seen to be supplied from a rock seam at a 
distance of 150 feet. Part of the ground water of Fishers Island is 
known to come through crystalline rock from the Connecticut main- 
land, 3 to 4 miles distant. 

CONTAMINATION BY SEA WATER. 

The Connecticut wells which have been contaminated by sea water 
are within 200 or 300 feet of open salt water, on old salt marshes, 
along tidal streams, or on islands. They are practically all in rock 
where the surface water has presumably been entirely cased off. 
The surface water, however, is usually fresher than that derived from 
the rock itself. In a well drilled for the Norwalk Iron Works Com- 
pany, Norwalk, at an elevation 10 feet above sea level, fresh water 
was found in sand and gravel deposits at a depth of 60 feet, but salt 
water only was obtained at lower levels in the rock. The well was 
accordingly plugged at a depth of 60 feet and the rock water excluded. 
At many points along the coast pipes have been driven in deposits 




Figure 30. — Diagram illustrating the manner in which a well near the sea may be contaminated by salt 
water during the dry season. A, normal water table; B, depressed water table. 

of sand and gravel near the shore and abundant supplies of fresh 
water have been obtained. These wells may, however, receive incre- 
ments of salt water when the water table is brought below sea level, 
either by pumping or by dry seasons. In deep-driven wells near the 
shore which derive their supplies from the bottom of closed tubes, 
the head of fresh water is almost without exception sufficient to pre- 
vent the inflow of brine. In New Haven a series of wells have been 
driven through 6 feet of salt water into the sand deposits below and 
have obtained good supplies of fresh water. 

In wells deriving water from rock in which the supply necessarily 
comes through fractures it is possible that the fractures may have 
such position as to give more ready access to sea water than to fresh 
underground waters. The possibility of contamination by this 
process increases rapidly with nearness to the sea, especially if the 
rock outcrops beyond the shore line. Figure 30 represents the 
direction of circulation of water contributing to such well, the ground 
water above the rock being entirely cased off. 



CHARACTER OF GROUND WATER. 175 

RELATIVE VALUE OF WATER SUPPLIES. 

Experience has shown that water in Connecticut is to be recom- 
mended for domestic use in the following order: (1) Surface sup- 
plies, preferably from lakes that are constantly under supervision and 
subjected to frequent inspections and examinations; (2) deep wells 
so located that the surface area contributing to them is known to be 
free from contamination; (3) springs, especially deep-seated ones, 
like those along fault lines known to derive their water from regions 
not subject to contamination; (4) shallow wells and intermittent 
springs; (5) lakes and streams whose character has not been carefully 
determined. 

ANALYSES. 

In the following tables of analytical results the data are given in 
ionic form, in parts per million, having been recomputed, if not 
originally expressed in that manner. The column headings are in 
general self-explanatory. " Total solids" indicates the total dis- 
solved matter found by evaporating a measured quantity of water 
and weighing the dried residue. " Organic and volatile matter " rep- 
resents the difference in weight between the dried solids and the solids 
after being ignited at low red heat ; the figure serves as a rough meas- 
ure of the organic matter, though it also represents loss of water of 
crystallization, volatilization of some inorganic constituents, and 
other factors. The term " total hardness" is given to a figure 
found by adding standard soap solution to a measured amount of 
water till the mixture forms a good lather when shaken vigorously; 
the equivalent of the quantity of soap consumed is usually ex- 
pressed as calcium carbonate (CaC0 3 ). The " permanent hardness " 
is found by adding soap solution to water that has been boiled and 
filtered; it represents the hardness due to calcium and magnesium 
in equilibrium with acids other than carbonic acid. The "temporary 
hardness" is estimated either by subtracting the permanent from the 
total hardness or by titrating the water with normal acid. 



176 



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CHAPTER IX. 

WELL CONSTRUCTION IN CONNECTICUT. 

DUG WELLS. 

The common type of well in Connecticut is naturally the most 
primitive type — an excavation in the ground to a depth below the 
level of ground water, the interior being lined with brick or stones. 
These wells are usually dug in clay, sand, and glacial drift, but a few, 
where the surface material is shallow, are blasted into the underlying 
rock. Some wells are dug into rock and water is obtained from 
crevices, but in general the rock excavation serves merely as a reser- 
voir for water draining from the drift. Such wells are usually 2 to 4 
feet in diameter inside the stone casing and from 10 to 50 feet in depth. 

Very few dug wells are properly constructed in Connecticut and 
many are extremely old, it being not unusual to find wells sunk more 
; than a hundred years ago. The ordinary stone casing is very inef- 
ficient as a protection against the entrance of surface water, the 
openings between the stones being in many wells large enough to 
permit the passage of rats and other small animals. Brickwork is 
used as a lining in some of these wells, but probably the safest method 
of protecting such a well against contamination is by tiling. 

Too much care can not be taken in the location and protection of 
open, shallow wells. A well of the open type containing clear, 
sparkling water has been considered one of the most valuable posses- 
sions of home. Such wells are, however, peculiarly liable to dan- 
gerous contamination. Many of them are located on low ground, 
because water may be procured there at less expense, and some are 
walled up with poorly cemented stone and either open or covered 
only with loose boards. The tops of many of these wells are but a 
few inches above the level of the ground and may readily serve as 
resting places for impurities carried by wind or on the feet of animals 
and men. 8 The advantages of the small drilled or bored well, as 
compared with a dug well, are the decreased probability of the 
entrance of impurities at the time the well is put down, less oppor- 
tunity for rats, frogs, and other animals to enter the well, and the 
ease of shutting out surface and seepage waters. It can not be too 
plainly stated that open wells are dangerous to health. 

a See a discussion of this subject by Crider, A. F., and Johnson, L. C, Water-Supply Paper U. S. Geol. 
Survey No. 159, 1906, pp. 74-75. 

180 



WELL CONSTRUCTION. 181 

As dug wells usually reach but a few feet below the level of ground 
water, any fluctuations of the water table materially affect the 
yield of the wells. In dry seasons the water table may sink below 
the bottom of the well, with a consequent total loss of supply. This 
loss of supply, owing to drought, is more noticeable in wells located on 
hills than in those along stream channels. 

Dug wells are of value in rural communities, but in cities and 
thickly populated areas they are extremely unsafe because of the 
general contamination of the soil and the impracticability of keeping 
out surface water. 

The average cost of a well of this type, as ordinarily constructed 
in Connecticut, is about one-fourth to one-half that of the average 
drilled well, but when it is carefully constructed and cased so as to 
admit water only at the bottom, the cost is not far from that of a 
well constructed on more sanitary principles. 

DRIVEN WELLS. 

For wells in sand and gravel a method of well construction is 
recommended which, although commonly used throughout the United 
States, is little appreciated in Connecticut. This is the driven well, 
consisting essentially of a pipe, usually 1 to 2 inches in diameter, 
driven into the ground by means of a heavy weight. These pipes 
are perforated near the base either by boring round holes or by cut- 
ting straight slits with beveled inside edges. In some wells the per- 
forated pipe is fitted with a jointed conical tip; in others a hollow 
open tube is fitted with a perforated section of some noncorrosive ma- 
terial and a sharp steel shoe, so that it can be driven directly into 
the ground. The contents of the tube are then washed out by water. 
As the water can enter the well only through the perforations, the 
position of the base of the pipe determines definitely the depth at 
which the water enters a well of this type, thus differing radically 
from a dug well, in which more or less water enters from top to bot- 
tom. Such wells are usually put down in a connected series known 
as " gangs," all connected with a central pipe or main through which 
the water is pumped. In very favorable localities large supplies may 
be obtained in this way at relatively small expense. There are sev- 
eral such gangs in New Haven; one of 34 wells at the Yale gymnasium 
which supplies the swimming pool with 150 gallons a minute was 
driven at a cost of $600. Another gang of wells furnishes the Yale 
dining hall with water for cooling, and 40 such wells, each with a 
diameter of 2 inches, are used by the Hygienic Ice Company. 

Wells of this type can be driven only into unconsolidated material, 
where the water horizon is in sand or gravel. Many places in Con- 
necticut are favorably situated for obtaining water from driven wells, 



182 UNDERGROUND WATER RESOURCES OF CONNECTICUT. 

particularly those towns along the main river valleys and near the 
coast where the sand deposits are heavy. The average cost of such 
wells is 70 cents a foot and the yield and character of the water ob- 
tainable at any place may be readily and cheaply ascertained by 
means of a single test well costing not more than $20 or $25. 

The quality of the water obtained from driven wells is largely 
determined by their location in reference to possibility of sewage 
contamination. Although derived from greater depths the water 
from driven wells of moderate depth is not necessarily better than 
that from dug wells situated in the same contaminated district, for 
the flow of ground water through sand and gravel is more rapid than 
through till, in which the dug wells are commonly constructed. In 
thickly settled communities the water of driven wells often shows 
contamination. There are many localities where unpolluted waters 
may be obtained by driven wells and this method of construction is 
advised for the Connecticut Valley lowlands, where larger yields 
and softer quality may generally be obtained from drift than from 
the underlying sandstone. 

DRILLED WELLS. 

Of the various methods of obtaining supplies of underground 
water, drilled wells should probably rank first in importance. Al- 
though the most expensive, they are most free from contamination 
and yield the most constant supplies. 

As the process of drilling wells is not generally familiar, it seems 
advisable to present a brief statement of the methods employed in 
Connecticut. The two main methods of well drilling are known as 
churn drilling and rotary or core drilling, the former being far the 
more common. A churn-drilling rig includes a movable boiler and 
engine mounted on a frame which is ordinarily drawn by horses or by 
traction. Attached to the front of this rig is a collapsible derrick 
which acts as a support for the rope and tools used in the drilling 
operation. The drilling tools consist of a heavy steel bit, with other 
devices, such as jars and sinkers, which serve to prevent wedging 
of the bit, to add weight to the blow, etc. The bit is supported by 
the rope, and by means of a walking beam or other device is lifted 
and allowed to drop suddenly 20 to 30 inches, giving a succession of 
blows at the rate of 25 to 40 a minute. The sharp edge of the heavy 
bit breaks and crumbles the rock where it strikes, and by continually 
twisting the supporting rope the bit is made to strike a new spot 
each time. The result is a round and even hole with a diameter 
slightly greater than the width of the bit. The diameter of the drill 
hole is usually 6 inches, although 8-inch wells are not uncommon. 

Owing to the presence of glacial drift, a layer of sand or gravel or 
till is usually traversed before the drill strikes rock. The unconsoli- 



WELL CONSTRUCTION. 183 

dated material carries more or less " surface water," which it is desir- 
able to exclude. To accomplish this purpose, the careful driller 
inserts a casing, consisting of heavy iron pipe with water-tight joints. 
The iron casing should extend from the surface to bed rock, and it is 
particularly important that a tight joint be made where the casing 
meets the rock. This junction should always be examined by means 
of reflected light from a mirror to detect the presence of any surface 
water. Water is kept in the hole during drilling operations, and after 
every few feet of progress the tools are removed and the well cleaned 
out by means of a "sand bucket," a hollow tube with a valve at the 
bottom. 

As the chief water horizon in drift is at the contact of rock and the 
overlying material, it is important to know the character of the rock 
mass encountered. This is not always easy to determine, for it is 
not an uncommon occurrence to strike large bowlders that lie many 
feet above the bed rock and may be readily mistaken for solid ledge. 
The driller may assure himself in this regard by drilling into the sup- 
posed ledge. If it is a bowider he wall pass entirely through it in the 
course of a few feet. Moreover, the nature of the rock will ordinarily 
indicate whether it is part of the underlying strata or a fragment 
carried from a distance. 

The rate of drilling, or number of feet a day, varies widely with 
the character of the rock, and the price charged for drilling is ordi- 
narily regulated by the driller's knowledge of the bed rock in the 
locality. In crystalline rocks — to which the drillers generally apply 
the term "granite" — the rate varies between 2 and 25 feet a day. 
The price for drilling in crystalline rocks varies between $2.50 and $8 
a foot, the average being $4.25 a foot. In such wells the same rate 
is charged for the surface material as for the rock, but the driller 
furnishes the casing without additional expense. In sandstone 
drilling is much easier and the average price charged is about $2 a 
foot for a 6-inch well. For an 8-inch well the price is 50 to 75 cents 
a foot additional. The average drilled well costs more than a dug 
well and much more than a driven well, but it possesses advantages 
not shared by the other types. 

Core drilling or "diamond drilling" has been employed with con- 
siderable success by one contractor in the western part of Connecticut. 
In this process the drilling tool consists of a rapidly rotating pipe, 
the end of which is edged with diamond fragments, chilled steel, or 
other sharp cutting material wdiich wears away the rock below the 
cutting edges and leaves a cylindrical core within the pipe. This 
core is broken off and removed by various devices, leaving a hole of 
the desired diameter. 

Drilled wells are far safer in sanitary respects than either of the 
other types considered. The process of construction is such that 



184 UNDERGROUND WATER RESOURCES OF CONNECTICUT. 

with proper care the surface water may be entirely cased off and a 
supply obtained from a sufficient depth to insure safety. It should 
not be forgotten, however, that fissured rock may have openings 
large enough to allow the passage of water without adequate filtra- 
tion; this is much more likely to occur where the rock outcrops in 
the vicinity of the well than where a mantle of glacial drift overlies 
the ledge. In one place near New Haven where the soil was only 2 
feet deep, gasoline leaking from a buried tank at a distance of 150 
feet entered the rock and was carried into a drilled well at a depth 
of at least 18 feet. The gasoline may have entered the well through 
a crevice or by percolation through the rock itself. Although the 
contamination of deep-drilled wells is possible, it is an unusual occur- 
rence and is generally due to imperfect casing. 

A dishonest driller may sink a deep hole into dry rock and arrange 
the casing in such a manner that the water from the soil and the 
upper surface of the rock enters and fills the hole, giving the appear- 
ance of a yield from a great depth. The water is large in amount 
and may show a satisfactory analysis. Sooner or later, however, the 
ground water establishes channels of ready circulation and any con- 
tamination from surface water may enter and penetrate to the bottom 
of the well. 

To give a minimum possibility of contamination the following 
points should be observed: The well, of whatever kind it may be, 
should be located as far away from and as high above sources of con- 
tamination, like cesspools, open sewers, and barnyards, as circum- 
stances permit; the well site should be selected where the glacial 
drift above the rock is deep, rather than on a thinly covered rock or 
on bare ledges ; the well should be properly cased — a point to which too 
little attention is paid in constructing either dug or drilled wells. 
The driller usually furnishes casing from the surface to the rock, but 
where circumstances indicate that more casing is needed for safety 
the owner should not hestitate to assume the slight extra expense 
required to insure absolutely safe construction. 



CHAPTER X. 
SPRING WATERS. 
INTRODUCTION. 

If the surface of Connecticut were level and the soil of uniform 
composition and texture, the ground water would tend to assume a 
plane surface at a small distance below the cover of soil. Such a 
water table would rise and fall with each increase and decrease in 
precipitation, but there would be no well-marked channels to con- 
duct ground water to the surface. Connecticut, however, is a region 
of topographic inequality and variability of soils and bed rock and 
the imprisoned waters find many avenues of escape. 

The normal outlet for ground water is near the level of lakes, 
swamps, and rivers, where it emerges in large amounts although 
rarely in definite channels. Below the earth's surface there are 
innumerable openings from which water is poured unnoticed into 
streams, lakes, or marshes along the shore line where salt water 
mingles imperceptibly with fresh. If the floor of Connecticut River 
were exposed suddenly to view by removing the water, we should see 
tiny rills issuing from cracks and seams and porous places in the rock 
and drift forming the river bed. 

To speak broadly, any definite outlet for ground water is a spring, 
regardless of its size or of the geologic conditions which surround it. 

TYPES OF SPRINGS. 

There are springs which emerge from the ground with a force to 
turn mill wheels and with a volume to float a river steamer. There 
are springs which come from great depths and furnish vast quantities 
of hot water. The springs of Connecticut are of another kind — 
small and widely distributed, containing cold water of exceptional 
purity, and those suitable for domestic purposes and local supplies 
are to be numbered by the thousand. 

The three types of springs commonly found in the State may be 
classed as seepage springs, stratum springs, and fault or joint springs. 

SEEPAGE. 

Many hillsides and lowlands bordering streams and ponds are 
saturated with moisture and the ground is soft and springy under the 
foot. This is especially noticeable during the early part of the year, 
when ground water is particularly abundant. These marshy places 

185 



186 UNDERGROUND WATER RESOURCES OE CONNECTICUT. 

are " seeps" and are caused by ground water returning to the sur- 
face from the rocks beneath. Such diffused seepage, rather than 
drainage along definite channels, is the normal method for the escape 
of water from the ground, and, in fact, it is only where this return seep- 
age is concentrated by some local geologic conditions that a stream 
issues from the ground as a spring. 

When seepage is restricted to a limited area it may form a seepage 
spring, in which the water slowly escapes from sands or gravels over 
a space of a hundred square feet, more or less. In its natural state 
a seepage spring is marked by the presence of water-loving plants 
and in many places also by the presence of an oily-looking scum or 
film on the water, which is often mistaken far petroleum but which 
in reality is the result of decomposing vegetation. The particular 
factors which have served to concentrate the water at this place are 
not always easy to determine, but ordinarily a slight difference in 
texture of the sands or the presence of a thin mantle of drift over 
rock is sufficient to bring the water to the surface. As a rule the 
water can be still further concentrated by digging a hole or sinking a 
barrel into the ground in the zone of most vigorous seepage, thus 
furnishing a small local reservoir which receives the ground drainage 
from a larger area. 

There is, of course, no sharp line between general diffused seepage, 
seepage springs, and springs proper, although the term "spring" 
ordinarily implies a distinct stream of water issuing with some force 
from an opening a few inches or, at most, a few feet in diameter. 
No distinct channel need be exposed at the surface, but there must 
be at hand a definite horizon or zone along which the circulation of 
ground water is sufficiently rapid to form a constant stream of ap- 
preciable size. 

STRATUM SPRINGS. 

The horizon most suitable for the transmission of large amounts 
of water is the plane between strata of different degrees of permea- 
bility. In such positions the water occupies a definite zone in some 
porous stratum and is confined by strata through which it passes with 
difficulty. A stratum spring may originate between two sedimentary 
beds, between drift and underlying rock, between clay and sand, or 
even between sands of slightly different structure. Where the edges 
of water-bearing strata are exposed at the surface, as in stream val- 
leys or in artificial sections, the water is allowed to escape and soon 
tends to excavate channels along which further progress is rapid. 

Where an impervious bed overlain by porous strata is exposed for 
long distances, a line of springs may be formed at the contact between 
the strata. Lookout and Raccoon mountains, in Tennessee, are bor- 
dered by a fringe of springs which reach the surface at the contact 
of the capping sandstone with a prominent bed of shale. In the 



SPKING WATERS. 187 

Snake River canyon, Idaho, a line of springs of great volume emerges 
from sedimentary beds underlying lava. The edge of the North 
Haven plain in Connecticut is marked by numerous springs. This 
sand plain is underlain by clay which forms a basement bed for the 
ground water, and where the beds are truncated by Quinnipiac 
River springs emerge from the bedding plane between the clay and 
the overlying sands. Similar conditions are reported from the Po Val- 
ley of Italy, where the water penetrates the sand and remains under- 
ground for several miles, finally emerging as a long line of springs 
where the water table is forced to the surface by more pervious beds. 
Probably 75 per cent of the springs in this State owe their existence 
to the concentration of water between beds of sand, clay, till, and 
rock. 

FAULT AND JOINT SPRINGS. 

Ground water occupies all open spaces within the earth's surface 
and moves along joints and faults and seams as well as between beds 
of stratified series. The rock walls forming the two sides of a fault 
are usually sufficiently separated to allow the passage of water and 
the fissure is usually of sufficient depth to permit a profound circu- 
lation. Ground water from a large area may be contributaiy to a 
single fault zone and may exert pressure sufficient to drive the water 
along the crack with considerable power. Most of the famous hot 
springs of the world are located on fault lines. Many small springs 
in Connecticut are located along faults ; a their temperature, however, 
indicates that the water in them does not come from very great 
depth. 

TEMPERATURE. 

The temperature of the ground below a depth of 50 or 60 feet is not 
affected by daily or seasonal changes at the surface, and the tempera- 
ture of water which comes from those depths is therefore subject to 
only slight variation, remaining at about 47°, which is the average 
annual temperature of the State. No hot springs are reported from 
Connecticut, and temperatures under 45° are rare. Of the springs 
recorded on pages 191-194 only five have temperatures less than 45°, 
and none over 55°. The well-known Arethusa Spring at Seymour 
has a temperature of 47°, which coincides with the average annual 
temperature of the State. In a nonvolcanic region like Connecticut 
the temperature affords some indication of the depth from which 
water comes, and the absence of high temperature implies that even 
in fault springs the occurrence of water is relatively a surface phe- 
nomenon. 

It is frequently reported that the water from springs is colder than 
normal in summer and warmer in winter. These statements, how- 
ever, are not borne out by the facts. 

a See map by W. H. Hobbs, in Water-Supply Paper U. S. Geol. Survey No. 67, 1902, p. 80. 



188 



UNDERGROUND WATER RESOURCES 07? CONNECTICUT. 



INTERMITTENT SPRINGS. 

If Connecticut received a uniform a ad evenly distributed rainfall 
and were forest covered, the springs of the State would be practically 
permanent in position and constant in yield. The rainfall, however, 
is not uniformly distributed, the region is partly woodland and partly 
farms, and the strata consist of many varieties of rocks and soil. 
The result is that some springs are constant, some vary in yield, and 
some cease entirely during parts of the year. The flow of a spring is 
much more constant than the rainfall, because water in rocks is 
absorbed and stored much more rapidly than it escapes, and the 
rainfall from a large area returns to the surface through a few chan- 
nels. The soil is a reservoir filled within a few hours and then allowed 
to drain off for several weeks. In Connecticut the supply of water in 
the soil is usually renewed by rain before the reservoir is emptied, and 
the springs are kept flowing at varying rates of speed. 




Figure 31. — Diagram illustrating conditions for intermittent spring. For explanation, see text. 

The fact that ground water returns to the surface gradually is the 
chief factor which insures permanency of flow and carries springs and 
rivers through periods of drought. In certain parts of the country 
the principal supply for rivers is furnished by ground water, and 
during parts of the year the only water which enters Connecticut 
brooks is supplied by springs and seeps. 

A spring which normally gives a continuous flow may become in- 
termittent during dry seasons. The hill shown in figure 31 consists 
of sand and till, which allows water to be absorbed in large amounts 
and to sink to the impervious stratum along which ground water 
flows to the surface as a spring at B. When the water stands at a S," 
temporary springs may form, which cease to flow when the water's 
level drops to u t." In unusually dry seasons the water table may 
sink below the second outlet, thus producing an intermittent spring 
from one that has been constant for several years. 



SPRING WATERS. 189 

MINERAL SPRINGS. 

All springs contain mineral matter in larger or smaller amounts, 
but its presence may not affect the color or odor or taste of the water. 
In a popular sense, mineral springs are those which are notable for 
the large amount of their mineral content, for some conspicuous 
characteristic of the water, such as color, odor, or taste, or for the 
presence of unusual mineral ingredients considered to be of thera- 
peutic value. Dissolved rock material is sometimes deposited about 
the mouths of springs in quantities amounting to several tons a year. 
Even the ordinary cold-water spring carries to the surface appre- 
ciable amounts of rock. It has been estimated that the combined 
activity of 900 ordinary springs in the eastern part of the United 
States results in piling up each year rock enough to form a block 10 
feet square and 2 miles long. 

Several springs in Connecticut are reported to have medicinal 
value. Many springs, however, pass as medicinal merely because 
they have a forbidding odor or taste, and prove on examination to 
have little in their favor. It hardly needs to be stated that dis- 
agreeable characteristics are no evidence of the therapeutic value 
of water. There are no springs in Connecticut with an unusual 
abundance of rare mineral constituents, and few that are conspicuous 
because of their color and odor. 

VOLUME OF SPRINGS. 

Springs vary in size from minute trickling rills to streams that give 
rise to small brooks. The amount of water in a spring depends 
directly on the available supply from which it is drawn, and this in 
turn is directly related to the amount of rainfall and to the size of the 
area which is contributary to the spring. The attitude and struc- 
ture of the rock are also important considerations. The rock may 
be stratified, may have open bedding planes of wide extent, or may 
be dense and massive. Its texture may be coarse or fine. It may 
be easily soluble or resistant to chemicals. Furthermore, the dis- 
tribution of farm and forest land and the relative position of hills, 
plains, and valleys have much to do with collecting water and guid- 
ing it along the channels leading to a spring. 

USES AND PRODUCTION OF SPRING WATERS. 

The chief use of spring water in Connecticut is for domestic pur- 
poses. Thousands of houses are supplied by springs, either in their 
natural state or covered and connected with pipes, and some small 
villages derive a large proportion of their common supply from such 
sources. Springs are so abundant and so widely distributed that 
most farm houses have spring water either directly at hand or easily 
obtainable by a short pipe line. 



190 UNDEKGROUND WATER RESOURCES OF CONNECTICUT. 

The dairying industry requires large amounts of cold water flowing 
regularly through the cooling rooms, and Connecticut is highly favored 
in this regard. 

Fifteen springs report sales of table water for 1908 and there are 
known to be many others which have more or less local use. About 
nine-tenths of the production is sold for table purposes. One spring 
is the site of a resort with accommodations for about 80 people. Dur- 
ing 1908 the output of water increased about one-third and the value 
decreased one-seventh as compared with the record for 1907. The 
sale of water from 15 springs for 1908 was 424,826 gallons, at an 
average price of 9 cents a gallon. 

The springs from which water was sold during 1908 are enumerated 
in the following list : 

Althea Springs, near Waterbury, New Haven County. 

Arethusa Spring, Seymour, New Haven County. 

Aspinock Mineral Springs, Putnam Heights, Windham County. 

Buttress Dike Spring, Woodbridge, New Haven County. 

Cherry Hill Spring, Hamden, New Haven County. 

Crystal Spring, near Little River, Middlesex County. 

Elco Spring, Bristol, Hartford County. 

Glenbrook Spring, Glenbrook, Fairfield County. 

Granite Rock Spring, Higganum, Middlesex County. 

Highland Spring, near Mount Higbee, Middlesex County. 

Hillside Spring, Meriden, New Haven County. 

Live Oak Spring, Meriden, New Haven County. 

Mohican Spring, Fairfield, Fairfield County. 

Oxford Mineral Spring, Oxford, New Haven County. 

Park Spring, Norwich, New London County. 

Pequabuck Mountain Spring, Bristol, Hartford County. 

Quinnipiac Springs, Montowese, New Haven County. 

Red Rock Spring, Meriden, New Haven County. 

Rock Ledge Spring, New Haven, New Haven County. 

Stafford Mineral Spring, Stafford Springs, Tolland County. 

Varuna Spring, Stamford, Fairfield County. 

RECORDS OF SPRINGS. 

The following table and notes include the available statistics in 
regard to Connecticut springs: 



SPRING WATERS. 



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NOTES. 



8. Located at the northern edge of Whortleberry Hill, a ridge of gneiss overlain by 
sandy till. It is situated in a large seepage area from which flows probably twice as 
much as issues from the spring. Although rock outcrops are near at hand , it is probable 
that the water comes from the till and is part of an underflow draining the ridge to the 
south. Water rises 6 inches above entering point. 

69. Inclosed by four sections of 3^-foot tiling sunk into the ground. Water comes 
from the fine white sand probably resting on a ledge of gneissoid granite. The yield 
to the bottling works is 5 gallons a minute, and the overflow is probably 10 gallons a 
minute, giving a total yield of about 15 gallons. The spring is located on a rather flat 
terrace at an elevation above the river of about 120 feet. 

On the hillside, 200 yards away from the Arethusa Spring and at an elevation about 
25 or 30 feet higher, another spring issues from light-colored gneissoid granite, with the 
structure planes dipping about 4° SE. into the hillside. Both these springs maintain 
nearly the same flow throughout the year. 

90. The water supply is obtained from three ponded areas located in a shallow 
valley and fed by springs. The topography is flat and the soil is porous. The run-off 
is accordingly small and the soil absorption large. The ground water is near the sur- 
face and emerges on a nearly level area at the contact of till and the thin overlying 
deposit of sand. 

. The following notes cover a few springs that are not listed in the 
table : 

Granite Rock Spring, Higganum: This spring issues between two large granite 
bowlders on the upper slope of a high hill, but no rock outcrops are visible. The 
water is piped to a bottling works. The spring yields between 20,000 and 25,000 
gallons a day, with a fairly constant flow, at a temperature of 49° F. when the air 
temperature is 77°. The output of the bottling works during 1905 was about 50,000 
gallons. A second spring, recently excavated, is said to issue from a crevice one- 
eighth inch wide in the ledge. 

Ausantowea Spring, Woodmont: Has been excavated to a depth of 20 feet through 
hardpan, sand, and gravel, the water horizon being in gravel. Flows 100 gallons 
an hour and varies little in yield with seasons. The temperature is 57° when the 
air temperature is 88°. The water is bottled and sold. 

Buttress Dike Spring, Woodbridge: This "spring" is in reality a flowing well in 
which water rises 18 inches above the ground. It is on the side of a steep hill com- 
posed of chlorite schist and overlain by a thin layer of sandy till containing numerous 
heavy bowlders. The water appears to come from a vertical cleavage joint in the rock. 

Springs of T. T. Wilcox, two-fifths of a mile southeast of Highland station: Three 
springs, two of which are reported by Mr. Wilcox to furnish 51 barrels a day, with no 
seasonal variation, at a temperature of 48° to 50° F. The only contributing area 
at a higher level than the spring is a hill with an elevation of less than 40 feet and 
covered with a thin layer of till. The water apparently reaches the surface by work- 
ing along the bedding planes between sandstone and red shale. This requires a 
movement up a slope of about 15°. 

Spring of Charles Parker, 1 mile southeast of Meriden: This spring is located on the 
west side of a hill composed of sandstone dipping southeast and capped with a thin 
covering of glacial drift. The water comes from joints in sandstone, as illustrated 
on page 136. The temperature of the water is 51° F. when the air temperature is 56°. 

Chalybeate Spring, Litchfield: This interesting spring, which was famous in the 
early days of Connecticut, was described as follows by James Pierce: "It issues 
from an extensive bed of sulphuret of iron, situated on the eastern side of Mount 
Prospect, 4 miles west of the village of Litchfield. The spring is copious and peren- 
nial, exhibiting in its course much oxide of iron and a white deposit." 

a Am. Jour. Sci., vol. 3, 1821, p. 235. 



BIBLIOGRAPHY. 

The following is a list of papers dealing with Connecticut waters: 

Ellis, E. E. Occurrence of water in crystalline rocks. Water-Supply Paper U. S. 
Geol. Survey No. 160, 1906, pp. 19-28. 

Fuller, M. L. Occurrence of underground waters of eastern United States. Water- 
Supply Paper U. S. Geol. Survey No. 114, 1905, pp. 17-40. 

Triassic rocks of the Connecticut Valley as a source of water supply. Water- 
Supply Paper U. S. Geol. Survey No. 110, 1904, pp. 95-112. 

Gregory, H. E. Connecticut [Occurrence of water]. Water-Supply Paper II . S. 
Geol. Survey No. 114, 1905, pp. 76-81. 

Gregory, H. E., Champlin, F. A., and Grant, C. L. Connecticut well and spring 
records. Water-Supply Paper U. S. Geol. Survey No. 102, 1904, pp. 127-168. 

Pynchon, W. H. C. Drilled wells of the Triassic area of the Connecticut Valley. 
Water-Supply Paper U. S. Geol. Survey No. 110, 1904, pp. 65-94. 

Rice, W. N., and Gregory, H. E. Manual of Connecticut geology. Bull. Connecti- 
cut Geol. and Nat. Hist. Survey No. 6, 1906. 
196 



INDEX. 



A. Page. 

Acknowledgments to those aiding 9 

Artesian conditions, figures showing. 48, 134, 135, 136 

nature of 48-50, 133-135 

occurrence of 96-97 

Ausantowea Spring, description of 195 

B. 

Becket gneiss, character and distribution of. . 31 
Bedding planes, occurrence and character 

of 107-108 

water in 105-109 

Bibliography of Connecticut waters 196 

Branford Point, coast near, map of 163 

coast near, water supply of 162-164 

Buttress Dyke Spring, description of 96, 195 

C. 

Chalybeate Spring, description of 195 

Catchment basins, figures showing 141 

Chlorine, distribution of 168 

distribution of, map showing 168 

Circulation. See Water. 

Climate, description of 20-27 

Coast line, description of 17 

Coast region, town in, water supply of 162-164 

Conglomerate, water in 106 

Connecticut River, flow of 29 

Connecticut Valley, description of 17, 19 

Contamination, causes of 53 

Core drilling, description of 183 

Cream Hill, precipitation at 24 

precipitation at, chart showing 23 

temperature at 25 

Crystalline rocks, character and distribution 

of 35-37, 54, 56-60 

distribution of, map showing 57 

faults in 38, 65 

joints in 37-38, 61-64 

literature of 54-56 

types of 54,56-59 

water in 37, 54-103 

circulation and storage of 65-77 

conditions affecting 60-65 

wells in 92-103 

contamination of 173-174 

depth of 92-94, 100-103 

limit of 93-94 

flow of 96-97 

locating of 92, 94-95, 101-102 

pollution of 92 

records of 77-91 

figures showing 77 

notes on 90-91 



Page. 
Crystalline rocks, wells in, success and fail- 
ure of 91-92 

wells in, water of, analyses of 176 

water of, quality of 92, 94, 166, 176 

temperature of 94 

yield of 92-94, 95-96, 100-103 

See also Igneous rocks; Metamorphic 
rocks; Granite; Gneiss, etc. 

D. 

Daubree, A., on ground water 55-56 

Davis, W. M., on Connecticut geology 39-40 

Drainage, description of 17-20 

Drift. See Pleistocene drift. 

Drilled wells, construction of 182-184 

Drillings, character of 59 

Driven wells, construction of 181-182 

Dug wells, construction of 180-181 

E. 

Elevations, data on 12, 13, 14, 16, 17 

Ellis, E. E., on ground water in crystalline 

rocks 54-103 

on occurrence and recovery of ground 

water 44-53 

work of 9 

Erosion, work of 33-34 

F. 

Farmington River, description of 19 

Farmington Valley, description of 15, 17 

Faults, figure showing 114 

occurrence and character of 33, 38, 41-42, 65 

relation of, to water 38, 114-115, 135 

figure showing 135 

springs from 187 

Fissility, effect of, on ground water 67 

Flowing wells, occurrence and character 

of 96-97, 133-135 

view of 98 

Forests, description of 20 

relation of, to run-off 27-28 

Fractures. See Joints. 

Fuller, M. L., on artesian conditions 49-50 

on ground water 53 

on wells in trap 129-130 

G. 

Gaylordsville, flow at 29 

Geography; description of 11-30 

Geologic history, outline of 31-34 

Geologic map of Connecticut 57 

197 



198 



INDEX. 



Page. 

Geology, descriptive, account of 34-43 

See also Crystalline rocks; Triassic rocks; 
Pleistocene drift. 
Glacial drift. See Pleistocene drift. 

Glaciation, topographic modeling by 11,3-1 

Gneiss, character and distribution of 36-37,58 

joints in 98-99 

water in 37 

wells in 98-99, 100-103 

Gneissoid banding, nature of 63 

Granite, character and distribution of 57- 58 

joints in 64,98 

views of , 60 

weathering of 96 

wells in 97-98,100-103 

Granite Rock Spring, description of 195 

Granodiorite, joints in 63-64 

wells in 100-103 

Grant, C. L., well records by 88, 126 

Gregory, H. E., on wells in Connecticut 55 

Gregory, H. E., and Rice, W. N., on Con- 
necticut geology 32 

Ground, humidity of 27 

Ground water. See Water, underground. 
H. 

Hardness, causes of 166-167 

Hartford, flow at 29 

Highlands, description of 12-16 

rocks of 32 

streams of 18 

town of, water supply of 157-160 

History, geologic, outline of 31-34 

Hobbs, W. H., on joints 63 

on rivers of Connecticut 16 

Holmes, J. A., on ground water 55 

Hoosac schist, character and relations of 36,38 

Housatonic River, fall on 18 

flow of 29 

Housatonic Valley, description of 15, 19 

Humidity, records of 25-27 

I. 

Ice. See Glaciation. 

Igneous rocks, character and distribution of. 35 

intrusion of 31-32 

water in 1 

Industries, data on 30 

Intermittent springs, description of 188 

figure showing, 188 

J. 

Joints, continuity of 66-67 

direction of 63-64, 112 

intersection of 67-68 

number of 70 

occurrence and character of. . 37-38, 40-41,61-64 

relation of, to water 47-48, 

65-70, 109-114, 141-142 

to water, figures showing 135, 136 

to wells 93 

figure showing 61 

spacing of 65-66, 112-113 

springs from 187 

views of 60, 62, 106 

width of .*. 69-70, 113 

water in, storage of 74-76 

See also Fissility; Schistosity; Triassic 
rocks; Crystalline rocks. 



K. Page. 

King, F. H., on ground water 51 

L. 

Lakes, area of 19 

Lava, flows of 16,33 

flows of, occurrence and character of 38-40 

Leakage, effect of, on water table 105 

effect of, on water table, figure showing. . 105 

Limestone, character and distribution of. 59 

distribution of, map showing 57 

j oints in 64, 99-100 

wells in 99-100 

Long Island Sound, streams entering 18 

Lowland, description of 16-17 

streams of 19 

town of, water supply of 160-162 

M. 

Map of Connecticut, showing distribution of 

chlorine 168 

showing distribution of rocks 57 

Marble, character and distribution of 36 

Metamorphic rocks, character and distribu- 
tion of 35-37 

jointing in, view of 62 

Metamorphism, occurrence of 32 

Mineral springs, nature of 189 

N. 

Naugatuck Valley, description of 15 

New Haven, humidity at 25-26 

precipitation at 22-23, 147 

chart showing 22 

temperature at 25 

winds at 26 

water level at, fluctuations of 147 

Nordenskiold, A. E., on wells in Sweden 56 

Noroton Heights, flowing well at 97 

flowing well at, view of 96 

North Haven, map of 161 

water supply of 160-162 

P. 

Pegmatite, character and distribution of 59 

Peneplain, formation of 33 

Percival, J. G., on Connecticut topography. . 13 

Permeability, relation of, to wells 46-47 

Phyllite, character and distribution of 36 

wells in 99 

Physiographic provinces, description of 12-17 

map showing 13 

Pleistocene drift, analysis of 138 

character of 42-43, 60, 138-139 

clay in 140 

contact of, with rock 142 

water horizon at 142-144 

figures showing 142, 143 

grains in, size of 140 

stratification of 139-140 

water-holding capacity of 139 

water in 138-156 

quality of 145 

storage of 140-142 

wells in 142-143 

cost of 147 

depth of 144-145 



INDEX. 



199 



Page. 
Pleistocene drift, wells in, figures showing. 142, 143 

wells in, notes on 151, 156 

pollution of 172-173 

records of 147-151, 151-155 

water in, analyses of • 178 

height of.'. 146-147 

yield of 144-145 

See also Till ; Stratified drift. 

Pleistocene epoch, land modeling in 11, 34 

Population, data on 30 

Porosity, nature of 45-46, 60-61 

Precipitation, amount of 74 

charts showing 21,22,23 

records of 21-24 

relation of, to water level 146-147 

Pynchon, W. H. C, on wells in trap 129-130 

Q. 

Quartzite, character and distribution of. . 36, 58-59 

wells in 99, 100-103 

Quinnebaug Valley, description of 15 

Quinnipiac Valley, description of 17 

P. 

Railroads, routes of 11-12 

Rainfall. See Precipitation. 

Rice, W. N., on Connecticut topography 14 

Rice, W. N. , and Gregory, H. E . , on Connecti- 
cut geology 32 

Rocks, permeability of .' 46-48 

porosity of 46 

relation of, to ground water 34 

to jointing 62-63 

to well digging 34-35 

Run-off, rate of 28 

relation of, to rainfall 27-28 

S. 

Saltonstall, Lake, water supply of 27 

Sandstones, Triassic, distribution of, map 

showing 57 

faults in, figure showing 114 

water in 114-115 

joints in 109-114 

direction of 112 

spacing of 112-113 

view of 106 

width of 113 

occurrence and character of 39-40 

quarries in 39 

water in 104-105 

leaking of 105 

figure showing 105 

quality of 132 

temperature of 132 

wells in 115-128 

contamination of 173 

depth of 131-132 

flow of 133, 135 

locating of , 135-136 

records of 116-123, 126-128 

notes on 124-126, 128 

water in, analyses of 177 

height of 132 

yield of 130-131 



Tage. 

Schist, character and distribution of 36, 58 

joints in 98-99 

views of 62 

water in 37 

wells in 98-99, 100-103 

Schistosity, effect of, on ground water 67 

nature of 63 

Sea water, wells contaminated by 92, 174 

wells contaminated by, figure showing.. . 174 

Seepage, figure showing : 45 

nature of 45 

Seepage springs, character of 185-186 

Sewage, contamination by 171-174, 182 

Seyoms, G. H., work of 9, 169-170 

Shale, water in 106-107 

Shale, black, influence of, on water occur- 
rence 39, 109 

position of 39 

Shetucket River, flow of 28 

Siphons, use of 95 

Smith, G. O., on water in crystalline rocks... 55 

Smith, II. E., analyses by 9 

Softness, causes of 166-167 

South Willington, well at, diagram of r . . 143 

Springs, conditions for 49, 185 

conditions for, figure showing 50 

fluctuations in 51,188 

list of 190 

notes on .195 

records of 190-194 

relation of, to joints 135-136, 187 

figure showing 136 

types of 50-51, 185-187 

figures showing 50, 136 

water of, analyses of 179 

temperature of 187 

uses of 189-190 

volume of 189 

yield of 190 

Steam boilers, water for 169-170 

Still River, description of 19 

Stockbridge limestone, deposition of 31 

Storrs, precipitation at 21 

precipitation at, chart showing 21 

temperature at 24 

Stratified drift, character of 139-140 

wells in, notes on 156 

records of 151-155 

water from, analyses of 178 

Stratum springs, character of 186-187 

figure showing 50 

Streams, growth of, figure showing 45 

Structure planes, nature of 63, 67 

Surface water supply. See Water supply, 

surface. 
Swamps, areas of 19 

T. 

Temperature, records of 24-25 

Thames Valley, description of 15 

Tide, effect of, on water table 52, 146 

effect of, on water table, figure showing. . 51 
Till, wells in, notes on 156 

wells in, records of 147-151 

water of, analyses of 178 



200 



INDEX. 



Page. 

Topography, description of 11-17 

formation of , 33-34 

relation of, to water level 71-72 

to water level, figure showing 71 

to wells 100-103, 136-137 

Trap, character and distribution of 59 

joints in 113 

view of 106 

ridges of, formation of 33-34 

wells in 128-130 

water in 107 

Triassic rocks, bedding planes in 107-108 

bedding planes in, water in 108-109 

character of '. 33 

distribution of 38 

fossils in 33 

faults in 41-42 

water in 114-115 

joints in 40-41, 109-114 

direction of 112 

spacing of 112-113 

width of 113 

stratigraphy of 38-40 

water in 104-137 

conditions of 104 

wells in 115-130 

records of 116-123, 126-128 

figures showing 110, 111 

notes on 124-126, 128, 129-130 

See also Sandstone; Shale; Conglomerate; 
Trap. 
Typhoid feA^er, cause of 170-171 

V. 

Valleys, descriptions of 15-16 

Van Hise, C. R., on ground water 54-55 

W. 

Warren, map of 158 

water supply of 157-160 

Water, underground, amount of 51, 52 

analyses of 168, 176-179 

character of 165-179 

circulation of 44-51, 72-74 

decomposition by 73-74 

direction of .. 72-73 

figure showing 45 

composition of 166-168 

contamination of 53, 165-168, 170-175 



Page. 

Water, underground, depth of 55, 93-94, 95-96 

horizon of 142-144 

figures showing 143, 144 

materials dissolved in 167-168 

quality of 94, 132, 145, 165, 166, 176, 179 

relation of, to geology 34-35 

storage of 74-76 

temperature of 52, 94, 133, 187 

uses of 169-170 

weathering by 96 

Water supply, surface, quantity available of. 28-29 

source and character of 27-28 

Water table, effect of leakage on 105 

effect of leakage on, figure showing 105 

effect of tide on 52 

figure showing 51 

position of 44-45, 70-72, 146-147 

figure showing 143 

relation of, to rainfall 146-147 

to topography 70-71 

figure showing 71 

Wells, contamination of 53, 

92, 165-168, 170-175, 180-184 

construction of 172, 180-184 

depth of 92-94, 

100-103, 131-132, 136-137, 144-145, 172 

flow of 98-97, 133-135 

fluctuations in 52, 92-94, 95-96 

locating of 92, 94-95, 135-136, 171-172 

pollution of 53,92 

records of ' 77-91 

figures showing 77 

notes on 90-91 

relation of, to geology 34-35, 97-100 

to joints 74-76 

figure showing 61 

to permeability of rocks 46-47 

success and failure of 91-92 

water of, quality of 92, 94, 110, 176 

temperature of 52, 94 

water in, height of 133, 143-144 

quality of 132 

temperature of 132 

yield of.. 74-76,92-94, 

95-98, 100-103, 130-131, 136-137, 144-145 

Willimantic, flow at 28 

Williman tic Valley, description of 15 



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